Temporal syntax only. This means no spatial or track dimensions.
NPT time support only. No SMPTE time codes or Wall-clock time codes.
When changing the media fragment portion of a URL the media is not immediately updated. You need to refresh the page to see the change. This is most noticeable when directly navigating to the video and adding or changing a fragment.
The user interface for identifying the fragment in the standard controls is ugly and needs polish.
The HTML standard includes an 'initialTime' attribute for obtaining the start time. There is no way to obtain an end time so I've exposed a 'mozFragmentEnd' attribute on the video DOM object.