That's what I immediately noticed - his grammar and processing speed is pretty slow and steady but his vocabulary is incredible. I mean, he's been studying for what, 2-3 years? I wouldn't be surprised if he was in like the top 1% of people studying Chinese, on top of the fact that he has a small company to run.
I took Chinese in high school and did ok. Didn't use it and have tried to pick it up twice as an adult and have yet to get the tones down in conversation.
Put a book in front of me, I can get it. Let me listen to someone speak it and I am lost.
Listen a lot, as often as possible. Watch TV and movies - there are many on Youtube and Youku. I like to convert interviews from Youtube into mp3s and listen to them during the day during down time. Pick a character in these shows and try to imitate their accent (stick to someone your own gender). Try not to read the subtitles (even the Chinese subtitles).
If you want to go further, strip out voice clips from these TV and movies and put them into an SRS system (Anki, Mnemosyne, etc...).
Watch reality Chinese television with subtitles. You get both the visual confirmation alongside the sound. They can be kind of a drag to get through (esp if you're used to HBO-level stuff), but the benefit of reality TV is that you can miss parts of a conversation and not be completely confused as to what's going on as there is no real plot.
I find it really hard to watch foreign TV/Movies with subtitles because I lose almost all of the audio, and am pretty much just reading the whole time - path of least resistance to understanding, I guess.
Record yourself speaking and listen for mistakes. Hands down this is one of the best ways to improve your spoken ability in a language (even your native language if you want to avoid umms, and ahhs and so on).
Find a recording of a native speaker that has a transcript.
Listen to a section of the recording.
Record yourself saying the same thing.
Listen back to your recording for mistakes and problems.
Repeat the record/listen cycle until you are happy.
Move on to the next segment.
Finally the most important part and key to the whole thing: do it every day. If you do 30 mins of this a day then you'll notice minor improvements after about a month and significant improvements after about three months.
What the others are saying. The thing is, your brain is very plastic and will eventually grow new connections to process the novel sonic inputs -- but there will be some time delay involved. Not a lot will happen for a while. But then... a lot will happen. It will all start gelling, and making sense.
The key is to (1) watch/read/listen to stuff you truly love, and (2) make a sustained practice of it.
Beyond what's already been suggested: Work through the DLI tapes ("tapes"). They're good at throwing varied phrasing at you. For pronunciation in general, find an instructor who's good at teaching Americans how to make the sounds right. There are some mouth positioning tricks that are helpful. http://fsi-dli.yojik.eu/DLI/Chinese%20Mandarin/ for the DLI stuff.