Don't worry about the quantity of people who finish complicated RPG games,I think that just like 13% of people finished DAO,you can look at that in a sad way,but that 13% are usually the most mature fans,who are the ones who support the company the most,who are active on forums and baisicly the people who make the true fanbase,who support the game,the others are just there to give money to CDPR and Bioware,the ones who finish the game are usually the biggest fans who reccomend the game to their friends and who make the game popular and are the people who motivate the company to make awesome games becouse they have fans who love their games.
About the Witcher 3 videos,they are amazing,TW3 looks great,I can't wait,the monster hunting system seems amazing,the investiagion,information gathering,clues and rumors seem awesome,the combat sounds awesome,the monsters sound awesome.AWESOME