Speedie, jimlite, IPBC devs - the actual answer is this:
1. Hard-fork back to the original 10,000 block reward
2. Move decimal place over to avoid sub-one-satoshi coins (look into how IOTA did this)
3. All miners who mined 400 coins per block after the "fix" should be given (through a hard-fork) an additional 9,600 coins per block to the output address in their coinbase transaction
4. Continue mining 10,000 coin blocks as if nothing happened
This is the only way to fix this problem and return everything to normal.
Every other solution proposed has terrible trade-offs and edge cases except for this one.
As noted, that means mining would end in 4 months assuming the initial target of 1B total coins remained intact. So after 4 months we'd be left with video producers and viewers being rewarded with just the tail emission. I think that would kill the project quickly. They are, after all, the people who will decide the fate of the project in terms of widespread adoption of the IPBC platform, not miners or investors.
Alternatively you'd have to vastly increase the total number of coins, dilute everyone, and end up risking Litoshi markets.
None of this even begins to address how you would accomplish paying the miners between the fix and start of your proposed hardfork when working with an anonymous blockchain.