Suggestion to move introductory text
I agree -- much better and the layout works.
In this instance I set up a table. Left column for the activity box and right column for the videos. You're right, later in the tutorial the videos are embedded in the activity box. Works well if there is only one video, but harder to get the layout working with two videos -- hence the table solution.
One option might be to use two separate activity boxes -- one for each video? Although I think the layout is OK as it stands.