Complex sentence: The ASF container structure is patented in the United States (United States Patent 6,041,345 Levi, et al. March 21,2000) by Microsoft and Microsoft has invoked its patent against VirtualDub, a free video conversion program.
Split into simpler sentences: The ASF container structure is patented in the United States (United States Patent 6,041,345 Levi, et al. March 21,2000) by Microsoft. They have invoked this patent against VirtualDub, a free video conversion program.