LTS means long term support. Which means Ubuntu will support it for the next five years upon release. 16.04 LTS is released in early 2016, meaning end of life will be around 2021 (> 2 more years to go). 18.04 LTS is released early this year in 2018, and it's shelf life will expire around early 2023 (> 4 years).
And that's the crux of the matter - LONG TERM SUPPORT. This gives stability and predictibility to the base OS. Anything built on 16.04 may have a chance to run on 18.04, but the reverse is almost always not true.
To make HQPlayer work again, I'd have to modify the installation procedure to include software from the 18.04 series. The latest version of HQPlayer will work again, just bear with me.
