The Capture server is having issues processing HD videos from Fuse submissions. This seems to only involve iPhone users.
We have a support ticket open with the vendor to fix the issue and are hoping to resolve this by March.
Here is a link to a short video that you describes how to get around this bug. This will require re recording your submission in a lower quality.
Another option is to install the Techsmith Relay recorder on your laptop or desktop computer and transfer the iPhone recordings to your computer. The Techsmith Relay recorder application can then be used to upload existing media.