Lux

Well I don't really have a way of figuring it out unless I search around for who has recently taken their stuff down-- or just taken it down at all .3.

btw, could you link me to your youtube? It probably won't help, but kek, I'd like to check out your channel xD

My older bro reminded me that these channels might be of assistance:

Brony Music Archive: https://m.youtube.com/user/CappppperGeneral

Deleted Pony Music: https://m.youtube.com/channel/UCum2wSybQ474_wQteN4PV1A

A possible reason why artists are taking down music is because Youtube is issuing strikes against certain videos that may contain copyrighted material, and  monotization can no longer occur.  Whether its being investigated or not, if enough of a person's videos are flagged, your whole account could be terminated.  So some people prefer to sacrifice some videos that have this flag in order to maintain the channel as a whole.  Also, if all it is was music, then its possible the artist is trying to distribute their media via a different platform.  Like bandcamp or soundcloud.  A yet, another possible reason is that the person has moved on.  Some people leave their trace of fandom on the internet like a memoir.  Others prefer  to delete anything that they feel like they no longer associate with.