The PlayStation Video catalogue includes a lot of different series and videos that come with the latest releases on DVD (some movies come out even earlier) as well as classic black and white movies. The price tag on each movie varies greatly: you'll find movies for less than a euro (the cheapest ones) and others for six, seven or eight euros.
One of the benefits of PlayStation Video is that you can buy or rent any movie from your Android smartphone or tablet and stream it right from your Playstation 3 or 4. This is the main reason why you'll have to link your Sony user account.
PlayStation Video is a good official app for a service that simply isn't that great. We know it's wrong to compare, but when the competition is this fierce and goes by the name of Netflix or Filmin, the results are even worse. This app just doesn't measure up.