1. Paid and free version has almost same features. The difference is in paid version you can remove the demo logo and add your own logo to the player. Also, you will get option to add embed videos in video section.
Other than this all the features are same.
With Paid version we provide free installation and free support for 6 months
2. Yes it is possible to remove posted on and posted by. To do this follow the below forum link http://www.apptha.com/forum/viewtopic.php?f=27&t=2360
3. What do you mean by video excerpt ? You will be able to change all the colors from administrator. It is available with free version also. You can try the trail version and see how this works.
For any kind of support contact us at firstname.lastname@example.org or chat with our experts through http://www.apptha.com