You can sign up, access through your Facebook account or start as a guest. Whichever method you choose, Voscreen is free.
Then you have to select your mother tongue, as the site will use it to test how much you have actually understood.
Next you will be shown a 4-5 second video segment ranging from a wide variety of genres (films, documentaries, songs, speeches, ads, and so on). You click on play, and when the video clip is over you have two choices: I understand (you are given a choice of two translations in your mother tongue for you to click on the right one) or Show me the script (the transcript of the video segment is shown with the correct translation in your mother tongue highlighted in green).
H/T to Larry Ferlazzo.