the x940bt says it plays any MPEG-4 video formats. So I took a few videos I had which were in an mkv format and converted them to mp4 using mp4tools. I attempted to play them on my x940bt and it doesn't work!

Any ideas how to get .mkv to work or ideas on converting the .mkv to mp4?

handbrake (the app, not the thing on your car)?

Make sure your conversion to mp4 has the correct video settings. 320 x 240 is recommended and 640 x 480 is the maximum . Play around with the different audio/video settings of your converter till you get the one that works best. Refer to page 221 of the Operation Manual.