The YouTube notes to this video are interesting:
Sue Lyon came into Donovan's life at the end of 1965. This was two or three years before he met his "Jennifer Juniper" (Jenny Boyd). Lyon had starred in "Lolita" and "Night of the Iguana" before meeting Donovan. The couple dated until 1967 when Sue ended the relationship abruptly. Donovan had evidently slipped LSD in Sue's and her friend's drinking cup at a party. Sue described her trip as "frightening and disturbing" and she "felt her self-control disintegrating". After this incident Lyon never spoke to Donovan again until 1975. The two are now good friends and Sue attended Ione Skye's (Donovan's daughter) marriage to King Ad-Rock (with the Beastie Boys).