Still display blue bar when beginning or end time are invalid
When either the beginning or end time are in an invalid format, the blue bar representing the cut video disappears. Entering a number in the correct format is now the only way to bring it into a usable state.
Instead, the blue bar could assume 0 for the start position and infinity (length of video) for the end position on invalid times. Then, it would still be possible to set a valid time by dragging the bar (and the user is not required to know the required format).