Sorry if this seems like a commercial message, but I would actually recommend my own
DVD - because it's got a very fine-grained progressive method of training for front rolls, and it actually teaches tobu-ukemi (break falls) in a safe manner before front rolls.
For higher levels of ukemi, and for what I think is the best instruction, there is
Bruce Bookman's.
Where mine is of particular value is for people who are having a hard time learning ukemi, are dealing with injuries or the like.
Best
Ellis Amdur