Videos are most often related to events, and we already have
events.scheme.org, so the YouTube links could go there.

However, there are also some useful videos that are not event-related,
such as the SICP lectures. Hence a video.scheme.org or media.scheme.org
could make sense.

Another way to approach the problem is that every subdomain could in
principle be a multimedia subdomain. For example, we could link to the
video lectures from the same one that has the written tutorials.