Matt,
I ran another test tonight.
This time I was syncing 38 mp4 files. The total size was 7.8gb. The files varied in size. Small ones were ~15mb. Large ones were ~750mb.
When the sync started, it came back and said 3 minutes remaining. This gradually increased while it synced the first file which was ~650mb. By the time the first file was synced, it showed 28 minutes remaining. It stayed on 28 minutes for a few minutes, and started decreasing. After about 15 minutes, the time remaining decreased at the same rate as the time elapsed. When the last track was finished, it showed 5 minutes remaining. It took ~1 minute more to wrap up, and it was finished.
I can't really comment on this as I do not know how the remaining time is calculated. With the high accuracy I see when syncing mp3 files, I assumed it was taking the total size of the sync queue and calculating the remaining time based on the transfer rate being experienced. Maybe the large variation in file sizes for the videos is distorting the time remaining. When I tested this over the weekend, it sat on 2-3 minutes remaining for 30 minutes.