BuddyPress.org

@rossagrant theme authors should add $content_width – it’s a constant used to set the maximum width of embedded content like videos. It’s a standard part of just about any well-coded theme like those in WP theme repo per requirement https://codex.wordpress.org/Theme_Review#Required_Hooks_and_Navigation

Add the following at the top of your theme’s functions.php file
/**
* Sets up the content width value based on the theme's design and stylesheet.
*/
if ( ! isset( $content_width ) )
$content_width = 600;

Measurement is in pixels. Change 600 as needed.