You can /filter the results to a text file, as you did, then use
/play #channel filename.txt to play the file to the channel. Something like this:
filter -ffc inputfile.txt temp.txt *blah* 500
.play #channel temp.txt
.remove temp.txt
This will scan inputfile.txt for lines matching *blah* and output them to temp.txt. Then it'll play temp.txt to #channel with an interval of 500 milliseconds and delete temp.txt.
