Youtube
it only uses active one of them
use youtubp or youtubpst;
rename this youtubpAjaxVerificSt.user.js

set fmt=18
personal configurations for youtube in fmt=18 High definition
replace title for more facilities rename video

useful

in
Windows Explorer / Tools / Folder options / exhibition
.......... it disactivates
To occult the extensions of the types of known archives

........ to show the extensions
.flv .mp4 .jpg .txt

######## DOWNLOAD VIDEOS FOR YOUTUBE IN BROWSER CACHE - Firefox
about:cache

in Firefox for download videos
in address bar
about:cache
view ..... Disk cache device - Cache Directory: -
copy address;
C:\Documents and Settings\user\.....\fqkgs4s7.default\Cache

post in ........
windows / execute / run(OK)

To open the folder where they are the archives

in this folder ........
To show / Details

click in .......
Date of the modification
..... The first archive in the folder is the last one had access

It pulls with mouse for a folder and rename;
according to order; the archives must have the extension;
.mp4 for fmt=18; e .flv for fmt=6 or standard of youtube

########/

Thus it will be able to open in its player of video
WindowsMedia QuickTime RealPlayer or its preferring