There doesn't seem to be a lot of footage of William Hamilton out there. However, here is one video where he explains the basic concept of inclusive fitness:
The existence of altruism in nature can be explained by thinking about the replication of genes. We need to descend to the level of the gene, rather than the individual, in order to see that the gene exists surrounded by copies of identical genes that exist in all its relatives - in particular in its close relatives, its siblings, who have a half chance of carrying a copy of that particular gene, its offspring, which also have a half chance, parents: a half-chance, cousins: one eighth, etc. Seeing this swarm of genes that exists around a particular one, we can then ask what is the behavior caused by this gene that is most likely to cause the propagation of this set of copies in the relatives around it.Inclusive fitness is a key idea in modern evolutionary biology - with substantial explanatory power. It is a general framework which covers both altruistic behaviour towards kin and what was once referred to as being group selection. However, so far only a few people have applied the idea to memes.
Perhaps people are thinking of memes as being "like viruses" - and viruses don't have much in the way of parental care and can't easily recognise their relatives.
However, as it turns out, this line of thinking is wrong. The exact same argument that Hamilton applies to genes in this video can also be applied to memes - with similar significance and far-reaching implications.
Just as individuals tend to behave altruistically to those with shared genes, so they tend to behave altruistically to those with shared memes. We see that in police, military and religious groups. Shared memes are also a big part of why your computer cooperates with your printer. Inclusive fitness is a general aspect of Darwinian evolution. It is not confined to genes - it also applies to memes - resulting in "memetic inclusive fitness". There is, in fact a considerable scientific literature on this topic - however, it doesn't tend to use the terms "cultural kin selection" or "cultural inclusive fitness" - and instead frames the issue in other ways.
Cultural kin selection is the primary explanation for cultural nepotism and cultural eusociality.
I plan to rectify the neglect of cultural kin selection (or "memetic kin selection" or "kith selection" as it is sometimes called) in my forthcoming book on memes - which will have a large section on the topic.
Update 2014-08-17: Some excerpts from my forthcoming book on memes are now online. See:
Tim Tyler, Tim (2014) Cultural kin selection
...and the associated links.