VideoOverview: Refactor the page to look better and work in landscape mode

With version 0.3.x VideoOverview page can be displayed in landscape
mode. Unfortunately the layout of the page is not really optimized for
this mode. This commit fixes this. It also adds a play button for users
who don't like swiping.
Search: Reuse newly added HeaderButton instead of custom element
YTListItem: Shrink font size and make the text span 2 lines

Many YouTube video titles are quite long. Any extra space we can get
to display them is important.