After the video The Danielbeast, fans developed an interest in the picture that was shown on Bree's bedroom wall. Viewers could not see the picture clearly and began debating about what it could be. Baphomet was one of the many suggestions thrown around (Satan was another). In later videos, the picture was changed to be of Aleister Crowley.
A screen capture from The Danielbeast (shown at top right) yields a blurry picture on her wall. It's unclear why fans likened it to Baphomet, but that seemed to be one of the predominant guesses.
When contrasted with a clear picture of Baphomet (see bottom right), it becomes unlikely that this picture was actually of Baphomet. Furthermore, although the picture on Bree's wall is very blurry, one can make out three figures: two adults and a child, in what is very likely just a family photograph.
Wikipedia describes Baphomet as: "an idol or image of uncertain provenance, depicting a being of heretical worship. The name first came to public consciousness during the suppression of the Knights Templar."
Baphomet was supposedly the deity that the knights templar worshipped. It is suspected that this deity is apocryphal because the Knights Templar who confessed to worship of the "deity" only did so under extreme torture. Many of them later recanted. The rendition of Baphomet we have today was actually drawn by Eliphas Levi.