There are some other “filter graph connection” frameworks out there.  Some even allow for directshow input

The main ones that “might” aspire to be replacements would be gstreamer and avisynth. The others are more like “players/transcoders that allow for input output pin style graphs”

Here they are

VLC has its own filters/splitting et al

gstreamer (also accepts directshow input to its graphs)

avisynth (accepts directshow input to its graphs through avisynth)

ffmpeg with its new libavfilter can do some graphing type stuff.  ffmpeg also allows for users to write their own libraries based on libavformat, so kind of like your own…custom filter, basically, I think.

avidemux can be scripted to add overlays et al: http://hack2live.blogspot.com/2009/09/blog-post_21.html but probably doesn’t count.

mplayer allows for extra filters et al.

MPC-HC is a “real straight up” player that uses just directshow filters, basically. whoa!

Graphedit, of couse, has its own filters and connections.