RogerS find one of those multi-memory format USB read/writers. Turn off the power on the 770 and remove the MMC card. Attach the multi-memory format read/writer and insert the MMC card into the device on a PC with the video or other multi-media support. Rip the move or other media directly onto the MMC card. If you are going to process the video/wav file first then rip it to a hard drive. Once done move the processed file to the MMC card. Eject the MMC from the read/writer. Place it in the 770 and boot the device. I would think this would be the fastest method available as far as data transfer goes and complexity.

Other options:
1.) If you have a wireless lan then use a PC or other device that can serve files via a web site. This method may be slower than using the read/writer. Plus additional complexity is required to set up a web server. I am presuming that you can use right click on the filename on the server and save it. I haven't played with the browser on the 770 yet.

2.) With a USB hub and other junk attached to the 770, then you could take a 1 GIG USB thumb drive and mount it on the 770 with your video. That will take some work to setup. I do have one mounted right now. I'll document it at some point.

3.) Set up ethernet networking on the 770. There again the complexity goes way up. First you'd have to download ssh/scp to your 770. Then you'd have to setup another PC with ssh or sshd. Finally, you'd have to configure the 770 to use ethernet networking.

4.) I am sure there's even more ways that will become available. For example, if someone ports an NFS or Samba client to the 770, then you would be able to mount these shares to the 770 and copy your desired files to the MMC on the device. At some point an ftp client could be created to access an ftp server with the files. Since python is now available on the 770, a bittorent client could bring files to the 700. All of these would require ethernet networking or a wireless LAN to be available to you.

5.) Unless someone beats me and compiles vblade for the 770, this is a very cool idea. Someone has already done this on the nslu2 device http://www.nslu2-linux.org/ .
http://www.linuxjournal.com/article/8149
http://www.coraid.com/support/linux/
http://en.wikipedia.org/wiki/ATA_over_Ethernet
http://sourceforge.net/projects/aoetools/

Greg