I think that Spectator Mode, Snapshots, and Custom Controls weren't really filler. They are brand-new modes. Wii Remote controls was also probably an actual update as well; Sakurai just nullified its usefulness by showing us custom controlls.
As you said, videos and basic technique updates (barring taunts and chargeable moves) may have been genuine "bundle updates". Returning items and pokemon might have also been intentional; however, the fact that the team is still in the process of refining the monsters' skins and (in some cases) models suggests that it indeed was the result of having nothing else to show.
Battle for the Smash Ball, however useless it was, is also probably a genuine update, since it did present "new" information that we wouldn't have gotten if not for E for All.
As you said, videos and basic technique updates (barring taunts and chargeable moves) may have been genuine "bundle updates". Returning items and pokemon might have also been intentional; however, the fact that the team is still in the process of refining the monsters' skins and (in some cases) models suggests that it indeed was the result of having nothing else to show.
Battle for the Smash Ball, however useless it was, is also probably a genuine update, since it did present "new" information that we wouldn't have gotten if not for E for All.