While trying to gather information for my recent SEPTA Unilens post, I discovered a newish railfan video channel with a large amount of up to date of front facing video content that can help with signaling research. Retired Railfan Horn Guy has been crisscrossing the country shooting a mix of front window and standard videos with special emphasis on SEPTA and, more recently, Caltrain. The latter is particularly useful given the impending demise of forward facing views on that line.
The guy is based on Long Island so naturally there is LIRR content, but he doesn't seem to have the same level of access as some of the other LIRR specific video channels that I suspect have insider access. Anyway, its a fantastic channel and good resource to bookmark.