People often watch various movies and videos on the Internet. There is plenty of videos – for people who search for specific knowledge or just want to relax in front of the computer. If someone wants to download youtube films, it is not so obvious, how to do it. Of course there is a possibility to create a list of favorite videos, when you have your own account or channel on this site. But the problem is that videos are not eternal – after some time they can removed by their owner or the administrators of YouTube. Some sites enable downloading video on the computer. You can also change the file format, for example while downloading from youtube to mp4 file. The format of file influences its size and the quality of the video. Various players also support various formats, so it should be taken into account. A downloader can also act as an mp3 converter – when the main information is contained in the audio, not the video. The downloading time depends on the length of video file and its quality.