Previously on HN: http://news.ycombinator.com/item?id=1809346
http://news.ycombinator.com/item?id=1624997
http://news.ycombinator.com/item?id=1624041
Before you submit a URL to HN, try this query on Google:
link:(your URL) site:news.ycombinator.com* new people have joined the site who haven't seen it.
* people who previously had no interest in ML became interested
* people have gained experience and insight which gives a new light to the video, perhaps having new things to say.
* the ability to comment on the older posts has been removed
The last one is probably the best argument against redundancy haters: HN expires the ability to comment on links after a time. So even if I wanted to not repost, I could no longer discuss this video, as the original thread is closed. Further, even if the comment period did not expire, there is no comment notification system on HN, making it very difficult to keep up with older threads that get new comments
The other points are however equally valid - reposting occasionally is fine. I'm sure you don't tell your friends "we discussed the time bob did $silly 3 months ago, we don't need to tell it again", particularly when there are new people around hearing the story for the first time. The best part about when it does come up again on HN - you don't have to participate, you can just ignore the redundant post if you don't care. Just because it is there, does not mean you have to read and comment on it!
EDIT: Apparently there is :) as it was mentioned here.
Whether the HN culture as a whole dislikes reposts is another matter (in my experience it does not) but it does take one argument away from the people who think reposts are contrary to what we do around here.