Kommentar zu Dewarim 12:24

לא תאכלנו THOU SHALT NOT EAT IT — This is a prohibition against the eating of דם התמצית (the last blood oozing through the cut of a vein: תמצית from מצה “to squeeze”) (Keritot 4b).

לא תאכלנו, על הארץ תשפכנו כמים, you are to treat it so that it becomes unfit to eat, just as is water when you pour it on the earth. It is not enough to hide it, as one hides wine or oil and other liquids which are designed as drinks.

This prohibits the dripping tamtzis blood. The term דם התמצית means the blood that drips at the time of slaughtering. Three types of [tamtzis] blood come out at the time of slaughtering: The first is black, the second is red, afterwards it gushes [which is not tamtzis blood], and afterwards it drips again. All three [the first two and the last one] are called the dripping tamtzis blood. The blood of the limbs is blood that has moved from one place to another — even though it is still absorbed and did not come out of the limb, it is forbidden. However, if the blood never left its original place then it is not included by the prohibition, “Do not eat it.” This is explained in Chulin (14a). (See Tosefos there)