Suppose I knew I was going to die in a few months or years (I don?t,
and hopefully won?t, but?). If I was going to write letters or produce
home videos for my two sons (currently aged 6 weeks and 2.5 years)
that they would receive each year on a particular date until they are,
say, 30 years old, what types of things should I say? What things
would they be most interested in hearing? How could I leave them
something to help them over time? I hope this question prompts many
insightful comments, and thoughts on related topics are welcome (e.g.,
same question to my wife of 10 years; how and when to send these
messages). [Note: A good answer should go beyond personal thoughts].

I would suggest that you divide your life into, let us say, 30
segments. Maybe the first segment was you from 1 to 5 years old. And
then relate your life then to their life now. The reason I suggest
this approach is that you could begin to repeat yourself year after
year.  It  would be a safe bet that the tapes your children had
received would be played over and over and over.  Sooo, each tape
would have to be new, with unheard stories and lessons and laughs..

A bit dodgy using a home video

In 15 years VCRs will be like 8 track tapes - seriously obscure

I also doubt that DVDs will still be with us

my husband went overseas when our children were 2 and 4 and we made
videos of him reading books to our children. you could video yourself,
your wife, and even your children snuggled up on the couch reading a
favorite fable. even if you live to a ripe old age they will enjoy it.
and so will the grandkids...