What Video/Movie types can be uploaded with GF?

There is no restriction within Gravity Forms. You can allow whatever type of file uploads you like. With video, you will likely run into timeout or max file size limitation, but those come from your Apache and PHP configurations. Gravity Forms can be configured to allow whatever file extensions you want. Small files which upload quickly should never be a problem. You may run into issues with larger files, but again, this is from your host, not from Gravity Forms.

It's all dependent on your host configuration. If you can post the text of your phpinfo or provide a link to it, we can point out where potential problems lie.

I recently saw someone alternately having trouble/success with files around 60MB (OK when under 60MB, errors when over 60MB) but this is 100% dependent on your host and the configuration there. phpinfo will help us help you. If you can add a php page to your site, we can create a page called info.php and insert this into it:

[php]
<?php
p h p i n f o ();
?>

(take the spaces out of the word phpinfo to make thes work. Security restrictions on the host here prevent from typing that out correctly.)

Save that on the server, and post the link to it here. It will be accessed at a URL like http://example.com/info.php