There are several places to download free videos. You would need to decide what type of videos you are looking for. One of the most popular sites is Ireel. They offer a lot of the newer videos as well as older ones.
They use SSL encryption and are safe from that perspective. They have various billing options. Be aware when you sign up, that you may be selecting a 5 day free trial which then bills at $34.95/month after it expires (it says it right on the button). I selected that and cancelled on day 3 during the trial. I also bought some movies a la carte, because those were the movies I wanted to watch. The playback quality is good, and it is licensed from Sony and Paramount, so it is legit.
Yes you can actually. first you download mozilla firefox by searching it on google because most sites work better with mozilla. Once you have downloaded mozilla go on that and google search Watch free (movie you want to watch goes here) online. browse around and you will find some good sites
There are many brands that offer online rental services. The most prominent of which is probably Netflix. However Blockbuster is also a well known example, though it has lost some relevance within the last decade or so. Amazon also provides a movie rental service.