For the problem of watching the last lines of something: a few options, you can pipe to tac, e.g. watch 'ls -l | tac' which reverses the lines of the output

For the problem of watching the last lines of something: a few options, you can pipe to tac, e.g. watch 'ls -l | tac' which reverses the lines of the output, or if it is something like a log file, you can forget about watch completely and just use tail -f, e.g. tail -f logfile.log which will print new lines as they are added to the file.