All articles have an indication of how long read it is on Esteem. Maybe add the duration of embedded video into that and there you would have it. You could no longer comment or upvote on things you haven't seen. But:

The most common bots wouldn't be able to upvote anymore, trailing votes, automatically upvote your favorite bloggers wouldn't be possible anymore. You would change a very large part of what Steemit is today.

And I kinda love it here as it is, imperfect yeah, but still a great place.