Tag Videos are online videos which are posted on media sharing websites, such as Youtube or Dailymotion. Usually a person will post a video answering 5-20 random questions about his/herself and then ask other people to answer the same questions.
Most of the time the questions will be related to culture, language, and where a person has lived or was born. Many of these videos will ask a person to answer questions in their native language or accent or in a foreign language or accent.
"This is a Jamaican Tag video sent to me by 'NosyYoutuber78' asking me about my accent and where I'm from.
Question 1: Where are you from?
A: I'm from Jamaica
Question 2: How do you write Jamaica in patois?
A: Rite ih eny way yuh taak ih, I prefa say Jamrock."
...and it will go on like that for awhile, and will be either informative, entertaining, or a complete waste of time depending on the personality of the person making the video.