You may need to install a codec program to supply the proper filters needed to play all of the appropriate video file types. Go to wherever you installed MediaLab on your computer and find the Utilities folder. Then open the K-Lite AV Codecs folder. Blair included a version of this freeware program for situations like yours.

All you should need to do is double click on the K-Lite_Codec_Pack_710_Full.exe file to install it. Try that and see if the avi files play in Windows Media Player. Then see if the videos will play in MediaLab by creating a questionnaire with a single movie type item in it.

Just in case you may need a more recent version of the K-Lite codec, you can find the most recent version of the full program at the following link

http://www.codecguide.com/download_kl.htm

A word of caution if you do visit the website: Make sure that you only download something by clicking the bolded blue text that says Download Full on the right side of the screen. Don't click the big blue button that says Download K-lite or the big green button that says Download; they are ads.