I had the same problem in several blogs when upoloading images. Only images, not videos.
This is my solution:
– open wp-admin / includes / image.php
– find the following lines:
// Set artificially high because GD uses uncompressed images in memory
@ini_set(‘memory_limit’, ‘256M’);
$image = imagecreatefromstring( file_get_contents( $file ) );
Change 256M to a more reasonable value according to your real php memory limit
That worked for me in 2 different blogs. I’d like to get a feedback on this possible solution