It will work if the tube is sealed and only open at one end that pokes up above the surface. Float it down to where you want then pull it to fill it with water so it sinks and deposts the feed in the right spot.
Ok not something your going to use very often but I can think of some swims that it would be impossible to fish with the clip up and cast method as they would be under overhanging trees and branches.
Its one of those tricks to keep up your sleeve for that just in case situation.
There is a simlar trick with a ballon and a paper clip that can get for example pike dead baits out miles further than any cast ever could.
Mind you nowadays people probably just get a bait boat ...but of course we all know that cheating
:wh