For those of you that have been having MW3 vault rendering and sharing problems, I have found a temporary fix. At first I couldn't get a video to render, it would only render the last second of the game and wouldn't let me watch it. But after I messed around with some older videos I had in my vault, I discovered that in order to get it to render you need to do the following things. First, do not fast forward through the video. Second, choose "cut" instead of "fade" when managing segments. This has worked for me in several videos now, and also uploads instantly to my Youtube. I'm not sure if this will work for everyone, but it should for some. If you have another way of doing it, please share your feedback. Add me on Youtube, or Xbox Live. Also, don't save clips to the same slots in the vault. If you've saved it to slot 1, and it failed to render, save it to a slot that has worked before. There seems to be some redundancy in the slots.
I'll have to try this tonight.
I've made 4 videos and on all four I've FFed on them and after uploading them it cuts the first 7-10 seconds off the vid.
If that doesnt work and you're getting the message Your file has been modified blah blah blah or it is temporarily unavailable, I have 2 tips that allowed me to render videos. First try unplugging and rebooting your modem. Make sure your connections are securely plugged in. Second thing you can try is to turn your xbox off and reboot it. Both of these have worked for me. Hope this helps some of you as I know it's a pain in the ass.