For browsing, previewing, searching, and organizing videos I created Video Hub App. The primary feature is scrub / preview thumbnails from inside the video as you hover with your mouse and an infinite scroll of all your videos. It also has a "filmstrip" view to see all screenshots at once.
I've had no problems with 20,000 videos in a "hub" and I've heard people pushing past 100k. JavaScript has no problem applying .filter() across this many objects quickly.
Each search is its own .filter method (inside an Angular pipe) so every search should be virtually instant. And since the screenshots are pre-extracted (the most time-consuming part of using the app), you should be able to infinite-scroll with no delays in loading previews.
I hope it is useful to some of you here.
https://videohubapp.com/en/
Open source MIT: https://github.com/whyboris/Video-Hub-App