>> They are unstable because they require huge amount of resources ...
This actually is not enough of a reason in theory for the programs to crash. The programs should stop the processing when they run out of resources and allow a graceful exit.
The root cause for crashes then, I am guessing, must be lousy code. Either the entire video editing industry has gotten used to it, so that they are not demanding better solutions and thereby the product companies are not prioritizing fixing these crashes, OR, there are some common libraries that they all using which crash, and these product companies feel helpless. Hopefully someone knows the actual answer! :-)
Huh? Almost every application just panics when it runs out of memory. Not least because it's actually difficult to do stuff without using memory within typical application frameworks.
When I was at college more than a decade back, I tested many applications under such conditions and my own application too. Most Microsoft's applications survived even with less than 100 bytes of RAM remaining and a disabled virtual memory! This included Microsoft Office, Visual Studio, et al. My own application survived too with a fix or two. Windows Explorer, funnily, crashed. Many non-Microsoft applications crashed.
More recently (2012), I tested two commercial Java profiler applications, JProfiler and Yourkit. They both survived without issues under such conditions.