Did she already appear on the debut MV of Red Velvet?
Netizens have found out Yeri on the MV of Red Velvet's debut song 'Happiness',
which was released in 2014.

Netizens who saw the picture of Yeri in MV showed their reactions like that
"it is true!, she already made her debut by MV",
"they should have made debut as five member at the very first time,,lol"
"there was another female trainee on MV", "the fans of Red Velvet would be still confused" etc.