That's a diifferent kettle of fish, you are echoing the lines to @Window and then using /savebuf.

What Dave is doing is /filter in - /filter out. For that /loadbuf - /savebuf works the same except slightly quicker.

BTW: Try those same examples with /aline replacing /echo. smile

This is how I /loadbuf a standard log with long lines. (Wrapped and indented grin)
//window @Logs | loadbuf -pi @Logs logfile.log