Where can I find some good live recordings of TMV?

Check out the treasure trove that is The Marble Shrine who has the largest collection of Mars Volta recording online:
www.themarbleshrine.com/
or
www.youtube.com/@themarbleshrine

For official recordings, there is also the official live album 'Scabdates' from 2005 and the Live EP from 2003. You can also check out their official YT channel which is www.youtube.com/@themarsvolta/videos