McDonald was released from Brentford at the start of this month having failed to secure a contract, despite having played in three pre season friendlies. Since then, he has been training with Wimbledon and has secured a month to month contract.
Scott came over from Australia to join the Saints, although ironically he wasn't connected with the club's own youth academy. He was considered to be a very bright prospect and was even introduced to the crowd at half time against West Ham in February 2000.
McDonald signed a three year professional deal with the Saints on his seventeenth birthday and he continued to blossom in both the Saints Under 19s and in the Australian youth set up.
Scott broke through into the first team in a Worthington Cup match, but failed to cement a place in a struggling side under Stuart Gray.
McDonald drifted away from first team contention, more due to attitude than any lack of talent. He was loaned out to Huddersfield, but financial restraints prevented anything more permanent.
Scott was released by the Saints, with Gordon Strachan feeling that our older youth players simply weren't going to make the grade in the Premiership.
"Scott is a talented striker who made a few appearances for the first team at Southampton, but was made surplus to their requirements when Gordon Strachan took over," Dons boss Stuart Murdoch told the club's official website.
"He has been with us for a while in training and he's done very well. He did well for the reserves against Portsmouth and showed us that he is capable of scoring goals.
"I'm pleased to get him in and now it's down to Scott to show that he can perform on a regular basis.
"If he continues to do well the chance is there for him. I think his strengths will complement Patrick Agyemang up front.
"He makes intelligent runs, is strong and is good on the ball."
McDonald is probably best in a position behind the front two. As so few English teams play this formation, he has had to adapt to being an out and out striker. While his goals tally could do with some improvement there, he certainly has the talent to create plenty of opportunities for others.