Can i change the dimensions of a video clip

send help how do i fix and not keep aspect ratio Image: https://d2r1vs3d9006ap.cloudfront.net/s3_images/1575767/RackMultipart20170331-88547-57usxt-hehe_inline.PNG?1490924571

Image: https://d2r1vs3d9006ap.cloudfront.net/s3_images/1575767/RackMultipart20170331-88547-57usxt-hehe_inline.PNG?1490924571

Image: https://d2r1vs3d9006ap.cloudfront.net/s3_images/1575768/RackMultipart20170331-31762-dz5j37-kkkkk_inline.PNG?1490924583

So i did a screen capture of this game that was a square but i want to make the video longer so i dont get black bars. When i try to drag it to increase the size its still a square. send help.