Looks like some smoke when it tries to start. Might try to spray some carb cleaner into the intake and see if it takes off for a sec or two longer. If it does then that goes back to the carb again. If not then maybe it has weak spark.
Did you set/confirm the proper gap on the new plug? Is the plug wet with gas if you pull it out after it sputters and stalls?
Did you set/confirm the proper gap on the new plug? Is the plug wet with gas if you pull it out after it sputters and stalls?