Playing in a suit contract

Whether to draw trumps, or ruff.
This video has some problems where very few participants found the right answers.
Can you do better?
You can replay the hands using the following links:
Draw trumps unless there is a reason not to: tinyurl.com/yy... tinyurl.com/23...
tinyurl.com/y3...
tinyurl.com/yae... If you can ruff 2 hearts you will make 12 tricks. Do not be tempted to ruff a diamond in your hand. It will not lead to any extra tricks and can lead to you losing control of trumps, if there is an unfavourable trump division. tinyurl.com/y9l... - only making 10 tricks, as you lost trump control.
tinyurl.com/y97... You reach a contract of 4S.
If you try to crossruff you may make only 11 tricks tinyurl.com/29...