well there's your problem!!!
you can just rename files to a different one to get them to load but the player will play them with the correct codec
of the correct file format.
maybe the changing of the format codec's is making the vlc program crash as it sees one that is not what it really is
and then it has to get the other codecs but still it trys to play with the codecs for what it is being called. confusing
the ?? out of vlc,, not sure if that is it but it seems to be the major connection for your error.
there are several video file converting programs for free that change the format to one you want.
by re coding the videos for you.
one i use is XMedia Recoder
i found it on majorgeeks.com its freeware,
does a fast and very good job of it.
you might want to make all your files the same format and see if the program will then play the whole playlist with out stopping. if it still does not fix your error then i suggest it to be a vlc error and you should contact them because monkey does not have code for video in mm 3 only this plug in script for the vlc player and that is a user created script.