Flash Player is required for some video streaming and apps on the web. GetFlash is tool that downloads and installs the latest Flash Player, written by Shinobar. Alternatively, download from Adobe's site, instructions on the libflashplayer page.

Install getflash-1.2.pet
Go to: PuppyMenu > Internet > GetFlash Install Flash

N.B. Adobe Flash Player 11.2 will be the last version to target Linux as a supported platform. Adobe will continue to provide security backports to Flash Player 11.2 for Linux.

libflashplayer - instructions on downloading from Adobe's website, and how to find Flash version
FlashExtractor - view and manipulate Flash files
Gnash - Open Source Alternative Flash Player

GetFlash app's thread
flashplayer-10.3.xxx pet (for older hardware) thread
Adobe's Flash download page