Hey y'all, total newbie to video editing here!

Tried to import my first files, cam .MTS files, but got no picture. I received a message like 'can't play mp4 files, need to download something', and did that, not working. Checked forum, saw that i could need some Media Splitter, downloaded that, still not working. Tried with a smaller, mp4 file too but same - get sound but no pic. Thanks in advance!