To change dimensions of your video, please head to My Videos >> Customize Video and change the size of your player to your desired dimensions.

By default, we set your player size to the dimensions into which the video was encoded.

Do keep in mind that when resizing a video player, you must preserve the original aspect ratio in which the video was encoded, else your viewers will see a stretched out(horizontal) or elongated(vertical) version of your video.

For example, if your original video was encoded in 480 x 270, the aspect ratio is calculated by dividing the width(480) by the height(270) of the video. In this case, the aspect ratio would be 1.77.
If you'd like to increase the width of the player to 640, for example, then the corresponding height would be 640 / 1.77 = 360. The optimal new player dimensions would be 640 x 360.