Note that the filing date of a patent application is not always the date by which prior art is measured. Here, the patent application in question claims the benefit of priority to a European Patent Application (EP 12184092.0) filed on September 12, 2012. So, the patent application in question has a priority date of September 12, 2012. In order to be considered prior art, the YouTube videos in question would have to be dated prior to September 12, 2012
The best type of prior art is that which has an effective publication date more than one year before the earliest priority date to which the patent in question is entitled. So, you really want to have prior art having an effective date of September 11, 2011 or earlier.