The average adult watches 3 hours per day. Given the OP's hobby-level interest in collecting the content, we can probably double that to 6 hours per day, which makes for 2.5 years worth of content.
Even though I'm squarely in the 6+ hour category, there are maybe 100 or so favorite movies that I've watched more than once, and once per year I'll re-watch a TV series (this year's revisit was Halt And Catch Fire). But even adding all of that together, we're talking about maybe 500 unique videos over ~20 years.
I can't wrap my head around needing to store 10,000 videos forever for the tiny chance that you might want to watch one that isn't still available through Usenet, private trackers or reasonable paid means.