While you can stream many videos from the web on your BlackBerry device, some video formats aren't supported, and some websites block content from being viewed on mobile devices. For more information about supported video formats, search the Help.
Tabs use memory on your BlackBerry device, and memory has a limit. The number of tabs that you can have open depends on how much memory you're using in other places on your device.
If you find you reached the limit on the number of tabs that you have open, try closing other applications that are running in the background.