Re: Time delay ...
Use a frame grabber to digitize your analog video and compress to mjpeg (motion jpeg). Buffer three seconds worth of the compressed video in a fifo; this can be easily implemented by a storage device such as a hard disk. Regenerate the delayed analog video by copying the fifo output to an mjpeg decoder with analog video output.
Added after 2 minutes:
If the application permits, you may not need to delay the video at all. Instead of delaying the video, try dropping some of the audio.