@LiveJohn Sorry, could you clarify your question? I have watched parts of some of their videos and been quite taken aback that they:
* present long "messages" of "seers" from Jesus, Mary and Saint Michael as being beyond question, while the Church has never pronounced on them as being of supernatural origin; and
* revelations about the Anti-Christ being named Alex and about how he is alive in the world now and about emerge at any moment (which means we have definitively reached the end of time. But, have we? Not according to Church approved apparitions) and:
* other apocalyptic, portentous developments, such as skin diseases that will attack the human race, etc., etc. -- a number of which clearly contradict prophesies attributed to Our Lady in approved apparitions, such as at LaSalette, and:
* the need for seeking out or setting up "Refuges" for protection as soon as possible to be saved from the impending Chastisement, etc....
...... ALL AS FACT
While I personally have no doubt that the human race is ripe for God's chastisement, and it seems to be approaching more and more rapidly -- a Chastisement already foretold by Our Lady of Fatima -- I cannot express how completely contrary to a Catholic Sense and practice it is for lay persons to set up a video channel to broadcast alleged "revelations" of a "seer" as FACT, and I find it truly alarming and lacking in due discretion. So I completely suspend judgment on the matter, as Catholics ought to. But many are led to follow them as "oracles", which is deeply disturbing.
Even Our Lady said ahead of time at Fatima that She would perform the Miracle of the Sun in October 1917 "so that all may believe....." so that the Faithful would have reason to place credence in what She spoke of at Fatima.
We have no such independent testimony concerning these "revelations" from either Heaven or the Church.
And even then, the Church exercised its authority to pronounce Fatima worthy of belief only after due passage of time and inquests to verify the nature of the apparitions was truly supernatural.
As Catholics, we steep ourselves in spiritual ascesis. We don't go running after "oracles" looking for a direct line to Heaven that's going to keep us "informed" up to the minute on the unfolding plan of God, thus opening ourselves to the possibility of error.
Rather, we have within us the light of grace to assist us simply -- and often heroically -- in conforming ourselves to the most perfect Will of God for us in any given moment.
THIS is the "revelation" we need: What is God's perfect Will for me at this moment.....how do I so perfectly surrender to Him that all my actions will be informed by His direction and divine grace?
And that's the only "revelation" God expects us to seek out through prayer, mortification, self-denial and blind surrender to Him at every moment in our lives.
I hope I haven't misunderstood the nature of your question. I simply wanted to address why I posted a "Disclaimer"....
God bless you!

@LiveJohn You said "So then, how do we sort out the wheat from the chaff - or valid from invalid?" Precisely the concern.....WE can't! I agree with you! That's the whole point!
And so, if we don't suspend judgment and we were to just follow such "revelations" as assured oracles of God speaking to us, we:
1) risk falling into error and...
2) quench the voice of grace within us which may wish to lead us rather to surrender in conformity to God's Will, rather than (selecting just two examples of "revelations") seeking out "Refuges" in which to hide from the terrible events to come, or seeking out "remedies" for any number of events we have been assured by one seer are about to beset us.
Neither of these examples from the alleged "messages" is the necessary call to repentance and conversion (a call we have already heard from Our Lady at Fatima, Lourdes and LaSalette)-- but rather an impetus to trembling fear and plans for self-preservation! But is it from God......?
And that's why I find it deeply troubling that two lay people have set up a YT channel which presents -- without qualification, without due discretion, and without even recommendations of discernment of any kind -- ongoing interviews with alleged seers (however pious and upright their intentions) -- presenting "revelations" and "messages" from Jesus and Mary and Saint Michael as indisputably true and FACTUAL! No Catholic has the authority to make such representations -- and then to chide those who don't believe them!
The Message of Fatima already calls us to radical repentance and conversion: the vision of souls falling into Hell and Our Lady's plea of "Many souls go to Hell because they have no one to pray and make sacrifices for them."
That one entreaty alone from Our Lady is enough to haunt me day and night to always live our Catholic Faith generously....not only for my own spiritual benefit, but for that of the many souls who may fall into Hell because I and others have not been generous enough in responding to grace and Our Lady's requests at Fatima....in fact, the "plan of life" She gave us which She said would win all the graces and help from God which mankind needs at this time.
You have mentioned Garabandal. A very, very holy Priest I know personally met with Conchita. He believes she was an authentic seer. However, do I need to know that for certain?
If the Church hasn't spoken, hasn't determined that the events were supernatural, what more do they add to Fatima, or Lourdes (where we heard the cry of "Penance! Penance!")?
IF...one day we all experience the "Warning"...or "Three Days of Darkness"... it is then it will be of consequence, and God will give us the grace then to know how to respond.
I personally believe we need the Warning and the Three Days of Darkness (we have curtains ready to be closed on all our windows ) because mankind has become so evil that this world is no longer fit to raise children in. So unless God cleanses the earth and converts the greater part of mankind, it's all over for the future of the human race.
But in the interim, we must live in surrender, not hankering to know at every moment what God wills next. That is why Our Lord said of the most consequential moment in human history -- His Second Coming -- "But of that day and hour no one knoweth, not the angels of heaven, but the Father alone....."
For now, all we need to know is that the cup of God's wrath is most assuredly filling up --- and we don't need new apparitions to tell us that. It's clear. And we also don't need new apparitions to tell us what to be doing now.....Penance, reparation, prayer, sacrifice and sanctifying ourselves at each and every moment of our lives by corresponding with God in the grace of each and every single moment of our day. And I believe we are agreed on that....