I've found that the 64 bit version does not work with the tutorial files very well. Doing the 2nd tutorial with Shot_tracked.mmf, it will only eat up memory, but not load the scene. Got up to 2gb used until I forced quit it. Opened it in the 32 bit version, it loaded almost instantly and seems to work fine so far.
Also, for those wondering about AVI or MOV export, those are 32 bit codecs. You have to have them installed on your machine for them to output to them. MatchMover DOES NOT come with codecs. Example: Since QuickTime is still a 32 bit app, so you will only be able to create an MOV with the 32 bit version.