From Second Life Wiki
TEXTURE_MEDIA
Description
Constant: string TEXTURE_MEDIA = "8b5fec65-8d8d-9dc5-cda8-8fdf2716e361";
The string constant TEXTURE_MEDIA has the value "8b5fec65-8d8d-9dc5-cda8-8fdf2716e361"
UUID for the "Default Media" texture
Notes
Like any string constants longer then 3 characters and used in multiple places in the code, they should be stored in a global variable. The result will be a considerable memory savings. See LSL Constants vs Globals for more information about this and examples.