In the resize filter Lanzcos3 is misspelled. It was named after Cornelius Lanczos so it should be spelled the same way. This seems to be a common mistake as Googling "lanzcos3" or "lanczos3" gives me 187 hits where they're both used in the same page.
In general, chasing typos consumes time missing for work on substance of the application. Readily making an exception for this one, thank you for noticing.
Typo fixed (https://github.com/mean00/avidemux2/commit/6db00f1a959fb14e58e5be2193b95e71c744f0ff) together with translation files (https://github.com/mean00/avidemux2_i18n/commit/537ae10294eca2de68b04b12d9bf2e68da659117).