Hi Harvey,
I recently did a CMS video interview for the CMS First Steps programme (for first years). These were the questions I remember they asked me (not exact wording just something along these lines)
1) Something general about what would you do when confronted with a difficulty in your work.
2) What differentiates CMS from our competitors
3) Describe a situation where you faced a problem and had to use extensive communication to deal with it.
4) Imagine you think you will struggle with meeting a deadline for a piece work a partner set you. What do you do?
I would recommend firstly practicing answering questions in the 1 minute they allow as I found this difficult! Make sure you don't spend too much time waffling on one point and neglecting/rushing others. Practice whilst looking at a camera as I found this slightly distracting in mine.
Think about some examples beforehand and ones for specific skills! I had thought of one example previously but was caught off guard by the question asking for a situation specifically using communication.
For the competitor question I spoke about their innovative approach with things like CMS by design, their in-house innovation hub. If I had more time and preparation I would have maybe discussed the vision of their 3-way merger and perhaps named their specific competitors in specific practice areas.
Good luck 
generally if you prepare for it well I think it will go smoothly.
