Sony appears not to want to document the ".411" file format, but it is clear from various web pages that it is a variant of the CCIR.601 standard YUV encoding used in MPEG. The name indicates that the file content consists of chunks of 6 bytes: 4 bytes of image Y values, followed by 1 bytes of U and one byte of V values that apply to the previous 4 Y pixel values.
There appear to be some commercial 411 file readers on the net, and there is the Java-based Javica program, but I prefer Open Source command-line utilities. So, I grabbed a copy of netpbm-9.11 from SourceForge and hacked the eyuvtoppm.c file so that it looks like this. While this may not be exactly the right thing to do, it produces results which are close enough for me.