Sorry for the wait, been on holiday. Lets see if I can remember all the steps. 1. Wire up the BluRay. 2. Build the disc at least once. This will make all the tmp media. Look in <project>/Sources/Menus/ and you will see the m2v file used for the background. This is the file we want to replace. 3. Save and close Encore. 4. Encode the background video as a m4v using Media Encoder. 5. Open <project>/ProjectMedia.acx and search for the m2v file. 6. Edit following PhysicalMedia data a. 'file' to point to the m4v file. b. 'size' to match the new m4v file size. c. 'codec' to be "H.264". 7. Save the file. 8. Reopen the project and rebuild the disc. Fingers crossed it should now use the h.264 file. I have noticed that Encode likes to randomly delete and change it's mind about cached files. So be aware that the edits you make may revert back with little warning. You may also find you need to manually delete the <project>/AuthorScriptHDMVSessions dir.