Andrea,
Per GG, it looks like the program failed in the lock window destructor (on a Quit). Almost all of the windows are gone but subtitles are still there. It could indicate an uninitialized variable and he did find 1 but not likely the 1 causing the SEGV. We both tried to run as ordinary users and load videos and quit but it did not error out for us.
I know you are busy with your brand new computer, but we are quite concerned that there is a problem not related to your new computer. So if you have time could you run as an ordinary user and get another dump if it crashes using the Ptrace option? This is documented in section 18.2 Crash Dump for Analysis.
(P.S. gg is very impressed with the new LaTeX version of the manual and wanted to pass onto you and Andrey his compliments).