Sounds like the Mactella is keeping it's TYPE and CREATOR attached to the files. Two things you can start out trying is first, if you ahven't already, go to your File Exchange control panel and specify that any video files; mpeg, avi, etc, be used with the Quicktime Plugin or Application. Second, for the files you already have, download the program Snitch, http://www.niftyneato.com/Snitch.html , get info on the files and change the the TYPE and CREATOR to be Quicktimes'. When you isntall Snitch you will need to add those to the Snitch lsit to choose from, whci will be under the Type and Creator pull down menu at the top right, and then down to 'edit list...'. Let me know if you need any help if with that.

Good luck.