Inserted Videos resizing themselves even when locked

I imported a video file via the developer tab by.....

1. inserting windows media player.
2. Using design mode to format video.

And the video resizes itself when play randomly.  I place it where i want it it grows obscuring the rest of the sheet.  I used tech support and they sent me here.  ALso sometimes using the mouse clicks makes it smallers with every click, i save it reopen it media does not play only audio