A trend that has begun over the past year or so has been putting virtual adds on the glass behind the goals during telecasts. The various Comcast Sports Networks, MSG and TSN are a few that have done it.
Sunday afternoon, the Capitals played the Buffalo Sabres in a preseason game (if you did not know because of all the football) at home. The NHL Network carried the CSN Washington feed, and they've added more glass advertising.
In the Capitals defensive zone, an ad for "Jeep" can be seen on the glass next to the Sabres bench and also behind the net as well.
Although distracting, I am not blind to the idea that this could become the norm for all other local hockey TV markets in the near future (FOX Sports, ROOT, Altitude). Perhaps even on NBC and NBCSN broadcasts.