I am assuming that you are referring to the small video boxes on HubPages. If so, videos will automatically be small if you align them with text. The will appear along side of a text box on the right. Check out this link from the Learning Center that explains the Video Capsule in great detail: https://hubpages.com/community/Learning-Center-vid
Check out the last paragraph on how to make the video small.
Hope this answers your question!