Is there a name for a speech impediment like this where, for lack of a better description, it sounds like you're talking after you've bitten your tongue?
「いだだきまあず」 → いただきます
「ごぢぞうざまでぢだあ」 → ごちそうさまでした
Here's the video I took the screenshots from, but the audio doesn't completely match the words on the screen. (Also, I couldn't figure out how to link between a particular start and end time on the video.)