Is it good to got Adobe Flash and Shockwave Player installed ?
of course, if you don't have a flash player plug-in for browsers, then you can't watch flash videos on internet such as YouTube videos (actually not just flash videos, you can't display any flash contents). i don't know if there are alternative flash players other than Adobe as a browser plug-in, and don't need to know coz the Adobe one is simply enough.

the shockwave player is also required to view some web-based applications. for further info see the link:
http://www.filehippo.com/download_shockwave/i suggest you install both of them if you still don't have them.