The cover art work was the same as the previously published paperback versions. The format of the dust jackets and their rather lurid yellow colour scheme gives them the appearance of video cassettes. Perhaps that was the thinking behind the design as renting VHS tapes was becoming more popular than buying books at this time.
Here are the titles that I’m aware of.
The Birthday Girl & The Birthday Treat - Robert Rush
The Medusa Horror & The Snake Orchards - Drew Lamark (Andre Launay)
The Innocents - Jack Godwin
Claw - Jay Ramsay (Ramsey Campbell)
Demon - Ivor Watkins
The Scurrying - Wes Whitehouse
Omen 4: Armageddon 2000 by Gordon McGill and Possessed by Alan Radnor are both listed on the back of some of the jackets as “also available in Macdonald Horror”. However, I’ve never come across either of these titles with the yellow dust jacket that matches this series. Does anyone know any different?