First, there's a version of Kindle with apps? (Probably something like "Fire".)

Second, I highly don't recommend listening to a foreign language with malfunctioning or low quality speakers (as, I think, they tend to be on portable devices). Really, headphones would be best... Anything that can get the sound closer to you and remove any interference.

I mean, I've got this kind of paradox - some videos I listen to I feel like I'm almost fluent, by how much I understand. Then I turn on a different video and get crushed. It could be just a different accent, but generally it seems to be the quality of recording. It shouldn't make such a big difference (it probably doesn't, in your native language), but add a little bit of echo and you can cut intelligibility in half.