Doing OCR Statistics past papers is always regarded as a necessary step to gaining confidence.
At first, past papers can be difficult and may take a long time to do, but if you stick at them, and do them regularly, then you should gradually notice that questions and methods become familiar the more you do. You will naturally speed up. The key is to never give in and also realise that there is often more than one way of tackling a question. It is good to experiment with different methods and compare the advantages and disadvantages of one method over another. If you can do this then you will be all the more better for trying it. Check out the OCR A-Level Statistics mark scheme and examiners report for further guidance.
I would encourage you to only look at the video / mark scheme after you have attempted the past paper question and/or looked at any accompanying tutorials.