Video stopped playing

I have a scene where at the very beginning a video starts playing and is fitted to fill the screen.

now, to add some interactivity, i wanted to add the controls bar bellow the video so I dragged the lower boundary a bit upwards to clear way to the bar.

the moment i did this change, the video won't play.

Moreover, about 50% of the time I try to preview the slide, it will "stuck" and seem to take forever to load.

when I press ESC and retry, it loads really fast and doesn't play.

when i use the CTRL+Z to place the video back in place, it loads really fast and plays as intended. 

I tried:

1. clicking it to use the default play/pause the video has.

2. create a new rule to play the video when the timeline is at 0.

3. click the control bar

again, the same scene and the only difference is where I resize the video a bit.