Additionally Additionally, They tend to stop working once the host site knocks them down for copyright violation. Which happens far too often, thus making even more of a reason we don't use them. (Being illegal is still the primary)
Even if its a legit video, some software such as Youtube's Copyright Content ID knock it down instantly because it is automated and can't tell the difference between a fan review, an official music video or an actual copyright abusing account. Replacing video is too much of a hassle.