Another upload problem is the inability to include a video preview when uploading a dream, which I believe may be due to a file size limit on the preview. Here's the error I received.
If the 2 MB limit is imposed on video previews, like the preview image, then the size is way too small and I will no longer be able to include one. At the lowest quality setting in After Effects, a 30 second dream preview file is 7MB.
On a positive note, I found you can manually insert a line break in the description by inserting the code <br>