Well, you can choose not to believe the tests shown in the vids. But why will the maker of the videos playing dirty just to downplay windows phone? Does it benefit him at all? I highly doubt so.
Being an user of windows phone and Android and iPhone, I can vouch that apps on windows phone are much slower than on the Android and iOS. Perhaps the apps are not optimized or OS itself is bad (W10M). Take Facebook for a start - notifications are received so much slower than the Android / iOS version when the app is launched. Loading of news updates / comments are taking its own sweet time too. Facebook Messenger is another crap piece - always waiting for connections when switching in / out of the app. Flipboard - slow refresh / updates. Instagram BETA - bad, simply bad. I know one may say "Hey universal apps are working much better". But look, ain't facebook suppose to be universal app already? TubeCast is also an Universal app too but the loading time of videos is slower than on the official Google YouTube app.
So you see, apps are just not performing well on Windows phone. Maybe you think I'm dissing the platform here but what I said above are my personal experiences with this platform. The OS is slick, but not the apps for sure.