I'm using Solidity 0.8.17, the video was using 0.6.x. So, when copying the code for the "MockV3Aggregator" I needed to change some things from version 0.6 to version 0.8. Changes:

• pragma solidity >=0.6.6 <0.9.0; --> it was "^0.6.0"
• import "@chainlink/contracts/src/v0.8/interfaces/AggregatorV2V3Interface.sol"; --> it was importing from "v0.6"

I was still having some issues running brownie compile. When I would try to run brownie compile, it would initially download Solidity version 0.6.12. Then, it would say:

"CompilerError: solc returned the following errors:

contracts/test/MockV3Aggregator.sol:6:1: ParserError: Source file requires different compiler version (current compiler is 0.6.12+commit.27d51765.Windows.msvc) - note that nightly builds are considered to be strictly less than the released version
pragma solidity ^0.8.0;"

I couldn't figure out exactly why it kept trying to compile using Solidity 0.6.12. I tried changing the compiler version in Visual Studio Code but that didn't work. Ultimately, to fix the issue and allow the code to be compiled without error, I added a version specification of 0.8.17 in the brownie-config.yaml file. To specify version, you should already have a hierarchy built out from earlier in the video that looks something like this "compiler >> "solc" >> "remappings". Subordinated to (underneath) the "solc" section, where "remappings" is, add a new section "version" and specify the version.