Pro tip: Search for games on runitback.gg, they feature a 2D reconstruction of the game with kill counts, angles etc... Once you've found a particularly interesting moment from that, go to vlr.gg and search for the match VOD and hope the observers caught it. That's a good way to find the multi-kill moments.
A method to find clips for particularly good frags would be to download the VOD chat and use messages-per-minute as a proxy measurement for when chat finds a particular play exciting(so you don't miss the non-multikill ones).
Easier, but more laborious methods are to obviously just go to the clips section on the twitch channel and click through all the clips or to watch the VODs.