His video on Karl Marx is below, and it is somewhat amusing, even though not always accurate.
Molyneux takes his critique of Marx from Paul Johnson’s Intellectuals (Harper & Row, New York, 1990), which is actually a very interesting analysis of Marx.
In turn, Johnson relied on these sources, either directly or indirectly:
Felix, David. 1983. Marx as Politician. Southern Illinois University Press, Carbondale, Il.
Page, Leslie R. 1987. Karl Marx and the Critical Examination of his Works. Freedom Association, London.
Tanner, J. R. and F. S. Carey. 1885. Comments on the use of the Blue Books made by Karl Marx in Chapter XV of Capital. Cambridge Economic Club, May Term.
Engels, F. 1971. The Condition of the Working Class in England (trans. and ed. by W. O. Henderson and W. H. Chaloner; 2nd edn.). Blackwell, Oxford.