It doesn't sound like a typical Yellow warbler to me (but they do vary).
The general pitch suggests warbler to me, but this bird wasn't moving. Not one bit. I was staring at this big tree for a good 20 minutes and couldn't get a view of it. Warblers generally move around a lot, so you can usually see where abouts they are, so I don't know what to think.
There were lots of Goldfinches around, but surely it is not one of them, unless it is a young male learning...