It was implied. Those opening sequences are hooks that reel us in. Powerful stuff!
Oh yes, sometimes the most horrific things are the things we don't see, those things left for our minds to slowly contemplate. It is one of the best devices for suspense with subjects that are so far beyond normal.
Sometimes it seems like in these days of CGI and also in some fairly violent movies, such as the Saw series for instance, the movie makers just show the audience things directly, which I think over time desensitizes the audience to the shock value of the subject matter.
But in the case of this past episode of Breaking Bad, not showing what they did and just leaving the implication along with the silence of the characters and the music of the scene was just masterful.
It is scenes like this that I think cause some people, including me, to say that this is the very best dramatic series on television right now and perhaps for some time.
These characters crossed over. They are on the other side now. They descended to somewhere dark.
Also I meant to answer another post earlier regarding what to do with Todd...I do believe I would have chosen option #2. He deserves it. Seeing through the eyes of Jesse, since I identify with him the most at this point, I would think to myself -well I'm already a killer by association, so if I'm going to be a killer, it might as well be for the right reason and not the wrong reason.- Then I would deal with Todd accordingly.