The actual video content and dialogue is typically dire. Many viewers will note in the comments that they muted the sound in order to increase their enjoyment of the video.
The term comes from a variation of the term "Youtuber," one who uses Youtube. We arrive at "Boobtuber," one who uses one's boobs to generate traffic on their Youtube channel, by substituting "Bob" for "You" in Youtube. This is also a clever play on words in that a "Boobtube" is also a ladies garment often sported by Boobtubers in their videos.
Boobtuber's videos are popular with young males who have strict (militant) parents that would severely reprimand them if they were found to be viewing dubious sites, whereas good wholesome Youtube is considered fine..."It's ok mom, it's only Youtube...etc etc"
Boobtuber's video comments section:
"Thumbs up if you clicked here for the boobs" (4567 thumbs up)
Scenario of young male with strict militant parents:
Billy: "Mom is it ok if I go on Youtube for 3 hours?"
Mom: "Sure Billy, what are you going to look at?"
Billy: "I'm interested in learning Japanese"
Mom: "Knock your self out Billy"
Billy --> Runs to the computer, fires up Youtube and searches for "Japanese word of the week,"
Wonders what the phrase for "Oh yeah baby" is in Japanese...requests that a video covers that specific phrase in the comments section.