I am also having this problem. I have my htaccess as:

php_value upload_max_filesize 100M
php_value post_max_size 200M
php_value output_buffering on
php_value max_execution_time 9999
php_value max_input_time 7000
php_value session.gc_maxlifetime 48800
php_value memory_limit 256M

i have managed to upload a file as big as 50mb without adding that in, but i had to try it 3 times and I dont think the average site visitor will be so patient. I've tested the import and got it to work on a short video, but on long videos I just get page not found.

Were you able to get your problem sorted out?