Well, it's also a wild compromise to say the warranty is void by installing popular software. If they would instead say, the warranty is void if you go above such and so threshold for such and so long (no matter with what software), that would make sense, but this, just seems a cheap way of making the warranty unexistent.

Anyway, a moderator from Dell replied that you can contact him if Dell refuses to give support just by seeing VLC installed, so maybe it's better than it seems.