Ya know, good question. Its going to take me a while to scour through Youtube to find any, but I'll definitely keep posted.
[edit] Went through some youtube links, I haven't found any that were using non-alphanumeric characters other than the underscore _ - but that worked fine as I tested a couple different links with that. I think Google hasn't started on those yet, so everything is working good so far.
[edit2] I broke it again. XD - [14:01:29] Tcl error [youtubesurl]: invalid command name "HD-720p" :: The title of the video is [HD-720p]DD ED, I thought it was the underscore, but it wasn't.