Hi Adam,
The file may also be too large to upload here in the forums - as there is about a 20 mb limit. So you may want to strip it down to that slide or remove video elements that could be contributing to the overall file size.
I did also want to share a link to this tutorial on working with the format painter. Since you have multiple objects you'd like to apply the formatting to, I wanted to point out the following tip: When you double-click the Format Painter button, it'll remain active until you turn it off. This lets you apply the same formatting to multiple objects. To turn the Format Painter off, just click it again or press the Esc key on your keyboard.
Please let us know if you need additional help.