Is appsrc the only way to get media data embedded in a file?

[Nikos Chantziaras]

This:

 
http://gstreamer.freedesktop.org/data/doc/gstreamer/head/manual/html/section-data-spoof.html

seems to discourage the use of appsrc. Is there a recommended way for 
playing media embedded in a file?

For example, there's a video in a file, and the video data begins at 
byte offset 100000 and ends at 500000. Is appsrc the only practical* way 
to play that?

* extracting the data into a new file, for example, is not practical.