Pasring HTML manually is not usually a good idea because it may break if site design is changed.

VKontakte social network has an official API. You can try calling API methods (get "https://api.vk.com/method/audio.search?...";) and decoding JSON yourself or use a module (for example, Net::VKontakte::Standalone which is a thin wrapper around JSON and WWW::Mechanize developed by me).

Registering an application can be avoided by passing any valid APP_ID (integer number). Methods requiring application secret to work won't work this way.