Clip speed

I would like to asks question in regards to using this app.

Im not familiar with the speed up process.

Im wanting to speed up my yoga video for a challenge on Instgram,and I can compress the video,but would like to know how to set the photo or video before I compress it so that it doesnt cut off half of my video (ie I only am able to get half of my body in the frame?)

Can you help me?

yogi_greeneyes_1 about Slow Motion Video & Speed Up, v1.4