Hi! Not having an audio track on the original video makes it a bit more complex, but the general principle should be the same. I suggest aligning the beginning of the video (using the visual clues that you have) and then going toward the end to figure out how big is the discrepancy. Also, from what I understood, you say that the video slows down too much after you try to correct it. It might be that you need just a minimum adjustment. In that case, I suggest using a higher level of zoom on the track. This will allow you to fine-tune the speed in a more precise way.