I saw some of the videos, however, they don't tell the entire story. For example, as I've mentioned above, the Ideapad S540 15-IWL comes with two battery variants - luckily, mine was available in 70Wh. However, for those, who wanted an extra hard disk cage, they have to go for the 52.5Wh battery. I've tried checking out the parts page, looks like that empty drive cage cannot be replaced with another fancy device, which is a little bit annoying.