Can you point to actual videos showing this, not just short out of context excerpts? Because I keep hearing this argument and every time I’ve looked I see a guy

Can you point to actual videos showing this, not just short out of context excerpts? Because I keep hearing this argument and every time I’ve looked I see a guy who has a speech impediment, but is otherwise quite sharp. Just looking at the presidential debates in their totality just showed for his age he was quite in command. The guy stutters yes but that doesn’t make him senile.