To play along in the same key as the first video in GCEA, put your capo on the 2nd fret (and note that an extra verse is added). The 2nd video is in the same key. NOW - don't get put off by all those Gmaj7, G6, Cmaj7, Am7. You can just play G and C if you want. But why not try those lovely chords. They're not hard and they add real beauty to the song (I think!).
"Que Sera, Sera (Whatever Will Be, Will Be)", first published in 1956, is a popular song written by the songwriting team of Jay Livingston and Ray Evans. The song was introduced in the Alfred Hitchcock film The Man Who Knew Too Much (1956), starring Doris Day and James Stewart in the lead roles. It reached the Billboard magazine charts in July 1956. The song in The Man Who Knew Too Much received the 1956 Academy Award for Best Original Song with the alternative title "Whatever Will Be, Will Be (Que Sera, Sera)".
A video for this song: