We're only using the seconds anyway, and some systems don't provide
st_mtim

Moreover, it was already present in the audio extensions list, but we
check the video one first.

Relying on ParserService to stop the thread was plain undefined
behavior, as the child class would have been destroyed already, meaning
the parser service thread was running using a dangling instance pointer

This fixes the progress not going up to 100%

opendir will fail soon enough if we're trying to open something which
isn't a directory