Merlin - 2008 Arthur's Bane Part Two 5-2 was released on: UK: 13 October 2012 USA: 11 January 2013
Mr- Merlin - 1981 Everything's Coming Up Daisies 1-15 was released on: USA: 1 February 1982
Young Merlin - 1993 VG was released on: USA: 1993
Merlin - 1998 TV was released on: USA: 19 October 1998
Merlin's Magic - 2013 was released on: USA: 1 May 2013 (video premiere)
Arthur - 2009 was released on: USA: May 2009
Merlin season 3 is able to be watched on Youtube. Check on Wikipedia to see the release dates. Only a few are out. Enjoy them :D.
Mr- Merlin - 1981 The Ache 1-10 was released on: USA: 23 December 1981
Merlin the Magic Mouse - 1967 was released on: USA: 18 November 1967 Finland: 15 October 1972
Mr. Merlin - 1981 A Moment in Camelot - 1.7 was released on: USA: 18 November 1981
Awakening Arthur - 2010 was released on: USA: September 2010
Arthur - 2014 was released on: USA: 25 April 2014 (internet)