Those videos most probably are .3gp and you don’t have any program installed in your Pc to play them.
Don’t worry, that’s the reason of 3gp player, as its name clearly shows, it can play 3gp videos with no problem.
Its interface is not eye-catching, ok, but it is really useful and you will not find any nonsense option. It is really easy to use, just run it and choose the file you want to play, that’s all.
In addition it does not consume a lot of resources and it is free, so double action, play your videos and keep running other applications.
3GP Player 2006 allows you to play 3GP files on your PC. It supports all mobile phone video formats including 3GP, 3G2 (3GPP2) and MPEG-4.
It requires QuickTime to be installed