You can extend search from your plugin, for example you could add an advanced filter like this:
require_dependency 'search'
if Search.respond_to? :advanced_filter
Search.advanced_filter(/with:video/) do |posts|
posts.where("posts.cooked LIKE '%<video %'")
end
end
The above will only display posts containing videos when the search box includes the with:video
keyword. See also the badge advanced filter for an example of a search query that takes user data into account.