Are we talking two different machines? Or is mala installed on a machine, the vids don't work in mala but they can be played via other means?
And what version of Mala?
If the vids don't play in mala, but do in other apps, it could be simply that you don't have mala configured to look in the right places for the vids.
If they don't play at all in any app, you may not have the right codecs installed.
I believe older versions of Mala did use a dll you'd need, but I'm not sure what it was called. The newer beta mala has all that compiled in (I think, Loadman could correct me though!)