There are three platforms that I'm aware of that are included in the Tildes SiteInfo dictionary—YouTube, Vimeo, & SoundCloud—that support linking to specific parts of a media resource via timestamps. This is useful to reference a particular portion of the video/song during discussion.
It should probably be possible to automatically apply hyperlinks to timestamps in the video (link this) when someone posts a comment with a timestamp-like string inside of it. This would make it a bit easier to share and link to specific portions of what's being shared in the main topic.
This seems like a decent value-add feature for Tildes. Whether it's a good idea to directly edit the comment string, I'm not so sure. I'd probably be in favour of implementing either a post-markdown middleware that added an icon next to the timestamp, kind of like how external links on some sites are suffixed with an icon that indicates the resource is not on the current domain.