If you open short possitions on ETFs and cover them within a year - that should be short term capital gain/loss.
If possitions are held more than a year - the gain/loss would be long term.
Let me know if you need help with reporting.
Some ETF's are short ETF's. Can I be long these ETF's for a year and pay capital
gains upon sale
If you purchase ETF shares as long positions - that is not your concern how that ETF is created - these are long possitions in your account.