Unsure if this has been posted anywhere yet, but this is not the first time this has happened.
Around 1998ish another modified P51 lost its
left trim tab, pitched nose up due to the highly nose-down trim, and the
pilot suffered from GLOC. Thankfully he recovered in this case
shows the full movement of the aircraft from the race-line to the crash-site.
From a completely uninformed point of view, it looks like the loss of the left trim tab caused pitch up and a little left roll as the aircraft was inverted, directing it into the crowd.