This is a passable documentary that concerns the military aspects of the Battle of Hastings as much as William's ascent to power. The reconstructions look authentic, certainly they are on a grander scale than those I witnessed at the 9th Centenary in 1966 as a ten year old lad, no cardboard lances on this occasion.
Although the Norman Invasion is usually alluded to as the last time England was conquered by a foreign army, this is debatable. As pointed out here, William the Bastard - as he was charmingly known - had a legitimate claim to the throne, at least in his own mind, and he was a cousin of Edward the Confessor.
William's greatest achievement was not though winning the Battle of Hastings but his commissioning of the two volume "Domesday Book", an invaluable resource for all serious students of English history, and one which is now available on-line. It's a shame this was not at least included, regardless of the years between his victory at Senlac Hill and its completion the year before his death.