In terms of features, there are no limitations - anything that is possible with api.video can be run in the sandbox as well.
The limitations that are in place are the following:
The maximum duration for videos in Sandbox is 30 minutes. If you upload a video that is longer than 30 minutes, it will be automatically cropped to 30 minutes.
The videos uploaded in Sandbox will be watermarked.
The videos are deleted after 24 hours.