ES5 Compatibility

With [this youtube-player release](https://github.com/gajus/youtube-player/releases/tag/v5.6.0), this package is no longer es5 compatible without transpiling node modules. Would it be possible to provide an es5 option, or possibly patch this package to lock it at [youtube-player@5.5.2](https://github.com/gajus/youtube-player/releases/tag/v5.5.2) and release a new version with es6?

Start by comparing the compatibility changes between youtube-player@5.5.2 and 5.6.0, then inspect this package's dependency and build configuration. Determine whether an ES5-compatible option or dependency pin is feasible, and verify the chosen approach with the package's existing build and usage checks.

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