For these cases I found this little bash snippet useful:

ls -tr | tail -n 1 | xargs -I FILE kde-open "FILE"

Instead of kde-open, which opens any file with the associated program, you can use any program, gnome-users might want gnome-open, people with other window managers can use xdg-open from xdg-utils. Or you can just insert mplayer, if you are only interested in music and videos.

I prefer it installed somewhere in the path, and then one can add a command-line parameter, the number of files to be played:

#!/bin/sh
ls -tr | tail -n ${1:-1} | xargs -I FF kde-open "FF"

playlast

ytplay wraps around youtube-dl.py, it searches for a video, orders youtube-dl to get it, and starts playing it in vlc.

Usage is simple:
> ytplay foobar
will search youtube for videos about foobar and play the first one found.

The code is still quite dirty, especially the subprocess part. However, it should work, have fun!

#!/usr/bin/python
# -*- coding: utf-8 -*-
#		parser.add_option('-P', '--play', action='store_true',
#				dest='play', help='play in vlc', default=False)

from optparse import OptionParser
from subprocess import Popen, PIPE
from urllib2 import urlopen 
from urllib import quote_plus
from re import search, match
from os import system

parser = OptionParser(version='2010.02.13')

parser.add_option('-p', '--player',
dest='player', metavar='PROGRAM', help='media player to use', default='vlc')

(opts, args) = parser.parse_args()

if match("http://",args[0]):
	videopageurl = args[0]
else:
	searchargs = '+'.join(args)
	searchurl = "http://www.youtube.com/results?search_type=&aq=f&oq=&search_query=" + quote_plus(searchargs)
	searchresult = urlopen(searchurl).read()
	p=search(r'(watch\?[^"]*)',searchresult)
	if p==None:
		print "No Videos found"
		exit()
	videopageurl="http://www.youtube.com/" + p.group(1)
	

print "Starting youtube-dl for " + videopageurl
ytdl = Popen("youtube-dl.py -t -b " + videopageurl,shell=True,stdout=PIPE)

while not ytdl.stdout.closed:
	line = ytdl.stdout.readline()
	print line,
	if line == '': exit()
	p = search(r'\[download\] Destination: (\S*)',line)
	if p != None:
		print "Starting player: " + opts.player + " " + p.group(1)
		system(opts.player + " " + p.group(1) + " &")

ytplay