starting a HIIT fitness video

Sounds normal to me. It's important to stop the video and not push yourself all the way through because you'll get discouraged. I recommend trying to add on a few minutes every workout, you'll get better and better and eventually be able to finish it.

Yes. You are doing great! Congratulations! You should be so winded during the work interval that it should take three to four times as much to recover. However, early on, you might not be able to do more than a few intervals.

My longest work interval is 30 seconds, with rests up to 120 seconds. I try to get between 5 - 10. So, with a five minute warm up, ten 30/90 intervals, then a five minute cool down, I’m done in thirty minutes. I’m sure working up to 45 minutes is possible, but don’t sweat it if you don’t.

There are two ways to go about improving your performance:
1) Take the planned rests for the first few intervals, then use the pause on subsequent rest intervals to extend the recovery time and get to a recovered state
2) Try to work further into the video each time adding one more work interval until you can do a full set.

Also, I wouldn’t do more than two of these a week. You risk overtraining if you do.

You're probably doing high intensity AEROBIC workout. Keep going, by pushing yourself gradually, you're doing great Eventually you'll be able to push your lactate threshold up if you push into ANAEROBIC zone. Good luck:)