Videos not being trackable is such a perplexing one. Is it intended to keep the user watching longer by forcing them to re-watch the whole video if they want to see something again?
Instagram is a Duke of dark pattern ux, I'd say king but there's travel booking websites out there that hold the crown.
TikTok on the other hand I think the video needs to be much longer to be trackable.
The white bar at the bottom, which shows the progress of the reel/video, can be dragged. It is a very buggy experience, but it works.
I think it doesn't work with very short videos.