FreeTube is a FOSS youtube frontend.

FreeTube occasionally has issues on videos with preroll ads where the video fails to play because the ad won't be fetched. This can sometimes be mitigated by running an ipv6 rotator script and blocking freetubes access to ipv4. The one I run reassigns my ipv6 address once every 5 seconds to a new randomly generated valid address.

Sometimes even this doesn't block the ads (again causing the video to fail to play) in which case selecting the share icon from the freetube interface and clicking "open invidious link" will open a web browser pointed to whichever invidious instance is set to your default.

The freetube folks are working on implementing DASH, which should eliminate the need for these workarounds once successful.