No you will not go to jail or be arrested for downloading movies from websites and through torrents or anywhere else.
What causes someone to go to jail for movies is when they download the movies and then illegally copy and sell those movies.
I've downloaded movies from Youtube and other websites before and never have I been arrested or even contacted by police or my ISP.
So as long as you're not selling the downloaded movies or claiming the movies are owned by you when you upload the movies to websites such as Youtube then you should be fine.
There are also legal ways to pay for and download movies and own a file legally of that movie but you cannot resell that movie you downloaded.