The Second Vatican Council forbids music to be used in Mass that doesn’t accord with the dignity of the Mass:
“[Recent] instruments also may be admitted for use in divine worship…only on condition that the instruments are suitable, or can be made suitable, for sacred use, accord with the dignity of the temple, and truly contribute to the edification of the faithful.” (Sacrosanctum Concilium 120)
And: “Let [composers] produce compositions which have the qualities proper to genuine sacred music.” (Sacrosanctum Concilium 121)
I think that Bishops are supposed to govern the admission of these instruments and musical compositions. In the case you posted, I think it is possible that some bishop wasn’t doing his job, though I would like to know the context to get a better understanding. Perhaps in that culture, the song that sounds to us like a carnival song has more solemnity.
As for the carnival-looking apparatus and roller skaters, I don’t see how that could be justified, but I’d like to see an argument from someone on the other side so that I could consider it in more detail.
Is this Church considered a “Protestant Church” as soon as something like this happens?
I don’t think a Catholic Church becomes Protestant whenever a liturgical abuse occurs.
How can these people at large be considered ‘Catholic’ in a 'Catholic Church" at all?
Perhaps it is related to this: it is my understanding that committing a sin doesn’t ordinarily remove you from the Church. If those actions were sinful, therefore, I do not think they would remove the participants from the Church.
Also, the video does have a point in that something like this could never happen within Orthodoxy. Would it be correct to say that? Or do similar things ever happen within the Orthodox Church?
What would stop it from happening? Opposition from the Orthodox bishops? I think the opposition of Catholic bishops is what ordinarily stops liturgical abuses from happening in Catholic cathedrals. The problem is when a Catholic bishop doesn’t oppose a liturgical abuse. I think the same thing could conceivably happen if an Orthodox bishop didn’t oppose a liturgical abuse. If someone argued that such a situation is impossible in an Orthodox church, I would wonder what he thinks would prevent their bishops from accepting such practices, and what evidence he has.