The fifth tail-nipping video I linked to shows a group of crows working along these lines, so one can see how it could be effective.
Since crows produce eggs, I don’t think we can rule out that it could have been for making omelettes. :o
Great sound-editing/choreography on that video, btw. 
Once again, off the subject of crows, but I’ve seen Kodiak bears in mating season playing a game that sure looked like “Tag” to me. Before getting to mating, each bear would “tag” the other, then run around in circles until the other caught him/her, then reverse the roles.
Back to crows… to me, the most interesting crow innovation is their use of automobiles. Seriously, this is a behavior crows COULDN’T come by instinctively, since automobiles have only existed for a little over 100 years. SOME extra smart crow actually watched humans driving cars, and figured out how to use them to his advantage. And his friends have done it ever since.
I have tweeted it!
Ars Tech happened to run an article today about Corvid behavior and intelligence. Recent studies suggest it compares favorably to chimp intelligence, which challenges the long held notion that intelligence is related to brain size. Primarily, the test studied self-control and an animal’s ability to forgo snatching fruitlessly at an immediate treat in order to puzzle out the correct route to the treat.
Here’s Ars’s article, which contains sundry links within.
I imagine this as a Far Side cartoon.
The notion that intellegence is correlated size of the brain, or rather, brain to body mass ratio, has long been understood to be applicable only within members of the same class (Mammalia, Mollusca, Aves, et cetera) given the dramatic differences in brain structure and distinct evolution of higher cognitive functions. Most ot the structure of the brain has little to do with higher cognition, but one distinct correlate across classes is the complexity in sensory perception; without exception, the smartest animals in class and order also have the greatest degree of environmental perception (often, but not exclusively vision) and the most complexity in the brain dealing with the processing of sensory data, e.g. the specialized features and expanded portion of the brain for interpreting auditory data in both spectral resolution and range in cetateans. The corvids, along with psittacines, have long been understood to be the most intelligent orders of birds, and demonstrating general cognitive and task-specific problem solving skills on par with a young child, including (in the case of macaws and African Greys) an ability to understand numeric and logical sequences and parse simple grammar.
Stranger
Thus, their intelligence ranks somewhere above the typical YouTube commenter.
I just watched these videos and am fascinated. I’ve never had a pet but now I want a crow! Actually would need 2, so that they could keep themselves busy.
From what I’ve seen, a nematode has more intellectual capacity and is more beneficial to society than the typical YouTube commenter.
Stranger
What do you people have against nematodes and corvids?