In the transition towards TMDB, many YouTube series/collections of videos will be lost, due to the more strict guidelines TMDB has on the matter. Most of my recent contributions to TMDB were deleted just for this reason, and some apps like SeriesGui.de will remove all series who do not exist on TMDB (like most of the Youtube series). This will also mean, probably, a major problem in transitioning from TVDB to TMDB for Trakt. Just letting a friendly advice out there, before wasting tons of your precious time in trying to import things that will be deleted.
If itās an actual web series, itās allowed just fine. 
I recommend Anne+! Season 1 was available on YouTube internationally before, but I think itās now on Netflix (along with Season 2), and season 2 also on Channel4 (UK).
Thatās the problem⦠the definition of āweb seriesā can be quite complicated to agree upon, and to a certain extent I donāt fault them about this. Iām just saying that this will bring some frictions with TMDB community, and that we will need to be ready for them, in case we want to help the transition here.
Several YouTube series seem to have disappeared from my Watched History and Progress Page this week.
e.g. āJay Lenoās Garageā, for which I submitted a support ticket, TMDB has no entry for the YouTube episodes but TVDB is up to date.