Yes and no.
It is illegal to download movies online if :
The material you have downloaded is without the owner`s consent.
Or the profit going to a different party other, than the owner of the material.
It is considered breaking the copyright law and, the consequences can be quite server including :
The loss of properity
Large fines
Imprisonment
Even in some case`s unemployment
In 2009 four men behind the illegal downloading website Pirate bay were sent to prison and ordered to pay $ 4.5 million ( £ 3 million ) in damages. That is how serious the court`s takes the matter with people breaking the copyright law.
But, there are website`s that allow you to download full length movies and even TV shows without you breaking the law .
Site`s such as Netflix which was established in 1997 offer 100,000`s of title`s which, you can either download on your computer, TV, Iphone, Playststion 3 pretty much anything with a internet connection all with the authors consent and not breaking any copyright laws.
with a excellent customer service and low monthy price its easy to see how in April 2011, Netflix announced 49.6 million subscribers worldwide.
And, even offers a free one month trail.