f. prohibited commercial uses shall not include -lrb- i -rrb- uploading an original video to youtube , -lrb- ii -rrb- maintaining an original channel on the website in order to promote a business or artistic enterprise , -lrb- iii -rrb- showing youtube videos through the youtube player or otherwise on an ad-enabled blog or website , subject to those advertising restrictions set out in 5.1 -lrb- e -rrb- -lrb- iii -rrb- above ; and -lrb- iv -rrb- any use that is expressly authorised by youtube in writing ;