How to fix the height and width of video played?

The best way I have found of supporting different aspect ratios is to create different content types for each one. The trick is to transcode into the right size for each video (eg from non-square 4:3 sources to square 4:3 output), and to set the display for each content type.

So for example, since 16:9 is the default aspect ratio, you can just focus on 4:3. If you're in Hong Kong and use PAL (4:3), you'd want to create a content type for PAL, but first you'd have to make sure you have your output dimensions in admin/config/media/video. You'll probably want to add these lines:

720x576
768x576
1024x576

Then create a preset for PAL where your source dimensions of 720x576 (non-square pixels) are transcoded to either square pixel format of 768x576 (4:3), or 1024x576 (16:9). This preset can be activated by the checkboxes in the video field settings, which will work regardless of what is turned on in admin/config/media/video/presets. That allows you to tune your transcoding, even if the display dimensions are overridden elsewhere.

Now create your content type (eg "PAL Video") and check the box for your PAL preset admin/structure/types/manage/pal-video/fields/field_pal_video.

The most important part is to set your player dimensions to 768x576 (square pixels) in admin/structure/types/manage/pal-video/display.

Finally, you'll probably want to create a couple of image presets for the poster image (eg "768w_pal" and "384w_pal_half"), which is also set in admin/structure/types/manage/pal-video/display. You'll need to compensate for the non-square pixels by setting both scale and resize. So for a full size poster for "768w_pal" you'd want Scale 768x768 and Resize 768x576; and for a half size poster for "384w_pal_half" you'd want Scale 384x384 and Resize 384x288.