I tried entering some times without seconds and when I did, :00 was automatically appended without me needing to type it. However, this only occurred when the time that I selected was part of the drop-down list.
For example: 05:40 auto-completed to 05:40:00, however, entering 05:41 and then tabbing out of the field erased the field.
There seems to be some validation occurring. This makes perfect sense. Perhaps prior to validation, the WebUI needs to check the length and add :00 if required.
Of greater irritation to me is the fact that the 'Stop time' defaults to 00:00:00 instead of the next value after the 'Start time`.
Unfortunately, these changes are probably of low priority as most users normally install TVH as a backend to a Media manager of some description and do not interact directly with the WebUI.