@KingCyrus, I do believe you mean that DemonOverlord is following the *tack* of making something non-human to explain it away. "Tact" has to do with social graces and "tack" refers to a course or heading. This of course in no way undermines your airtight reasoning of calling her Hitler, but I thought I might mention this briefly. It would demonstrate an extreme lack of tact, for example, if I were to invite you to kill yourself because of your egregious abuse of the English language; as such, that is not a tack I will take.
Now, as for your questions, I have, as many who support the murder of the unborn, seen videos of abortions. In fact, I have numerous pictures of this very act hanging in my room. I have baby parts that I bought from Planned Parenthood sitting in jars of formaldehyde as well. I got a good deal on them, so if you'd like to partake, just let me know.
You ask also how a heartbeat, brainwaves, and the capacity to feel pain do not constitute humanity. I offer very simple answers to this. First, the trinity of signals you mention are not exclusive to humanity, so relying solely on this to make the determination of humanity is silly. My dog has a heartbeat, brainwaves, and the capacity to feel pain, but she is not human. Second, does the absence of any one of these three constitute a loss of humanity? By your criteria, dead people--who lack heartbeats, brain waves, and pain receptors--are no longer human. This seems untrue, no?
I now refer to Peter Singer. There are two usual ways to define humanity. The first is that human beings are members of the species Homo sapiens. This is trivially true for all of our unborn, from the moment the sperm fertilises the egg, I should think. The second argument is that human beings are rational and self-conscious. A fetus is clearly not rational or self-conscious, and so this implies that its right to life, as it were, is not sacrosanct. (Incidentally, neither I nor Peter Singer has a problem with euthanasia).
I gather from your post that you are of the opinion that the first definition should hold, that membership in the species Homo sapiens should automatically grant this right to life. Perhaps, then, you could enlighten us as to why mere membership in a species confers this right.