I just added a review for the Fuze on Amazon that included info about transferring videos. So, I’ll just copy and paste what I wrote from there to here.
First of all videos have to be in mp4 format in order for the Fuze to be able to recognize them. Additionally, you have to use the Sansa Media Converter (which IIRC you have to download) to transfer those files onto the Fuze before they will work. That’s because the converter creates a metadata file called a thm file which gives the Fuze additional information that instructs it to play on your Fuze. So, you actually have two files added to your Fuze when adding videos, the video file itself (mp4) and the thm file. Your Fuze must be plugged into you computer in order for the Sansa Media Converter to work. Also, in order to successfully add the mp4 videos into the converter, you should close any extra video playing software. I’ve found in particular that having BSplayer open while trying to add causes problems for the converter. So close all media players. Another note on videos, there is third party software which will convert various media formats to mp4 format. DVDVideoSoft Free Studio is one such free utility. You just add you avi or wmv file (or whatever) to the utility using the video to iPod converter function. That will convert your video to mp4 format. From there you use the Sansa converter to transfer the new mp4 to your Fuze. If you have a fussy mp4 file that won’t transfer to your Fuze for some reason, just run it through the video to iPod converter and use this newly created mp4 file for transfer to your Fuze. I’ve only had that happen a couple of times, but it works. When the native memory on your Fuze becomes full, you may still want to transfer videos onto your Fuze via your memory card. Not a problem. Just use the Sansa converter as before. What will happen is that since your native memory is full the converter will tell you that the process has failed. That’s not completely true. It has failed to write the video onto the native memory, but it has still generated the video and thm file. The thm file, if you still had a little space left in native memory, is probably in the video folder of your Fuze native memory. Just go to that folder and do a cut and paste of the thm file from the native memory to a designated folder on your memory card. The video is still on your computer’s hard drive. Go to Users/[your user folder]/Documents/ Sansa Media Converter. Your video is in the Sansa folder. Just cut and paste it from that folder to the folder on you memory card where you put the thm file. Voilá, your video is now on your memory card, and your Fuze will see it just as if it were on native memory. You can also cut and paste videos, music, etc. from native memory and put it on your memory card if you want to make more room on native memory.
As far as videos freezing, IIRC it may have been a problem early on when I was trying to have the converter go straight from avi to transferring onto the Fuze. I think it has to do with having the converter try to do two things instead of one. When you try to get it to both convert to mp4 and transfer over to the Fuze, you end up with multiple problems. The converter software is really best to be used only as a means for transferring already converted mp4 files onto the Fuze. Once I started using the process that I documented above, the freezing completely went away. I’ve had my Fuze for months since early this year, and I haven’t had a freezing problem since I started following the above process. Also, using that process makes transfer of videos a lot faster than when I was trying to convert and transfer at the same time. I haven’t had any problem converting any video file regardless of size, resolution or frame rate since using the above process.
Does that make sense?