Shortcodes inside shortcodes.

Have you tried adding a new line between the shortcodes? i.e

[mycred_sell_this price="1" button_label="Purchase"]

[video src="http://mysite.com/mymedia.mp4"]

[/mycred_sell_this]

Which plugin are you using to get that video shortcode?

Thanks. I found the issue and will include a solution in the next update. You can resolve the issue until then by editing the mycred/addons/sell-content/myCRED-addon-sell-content.php file and on lines 604 and 680 replacing: return $content; with: return do_shortcode( $content );.