Super Mario Bros. X Forums

Is there a smbx 1.4.3? https://www.youtube.com/watch?v=nv_dzgA2sxY

no

Yes, but only for 12 seconds

SMBX 1.4.3 (Usually referred to as 38-A) is an unofficial version of SMBX developed by 5438A38A, which is generally not supported on these forums (I think, although I do sometimes use it myself). Most people here prefer to use 2.0, PGE, or the original 1.3.0.1 (Usually referred to as the Legacy editor), as 1.3(.0.1) is the official version by Redigit, which is no longer being developed, and 2.0 (With the PGE Editor) has support for LunaLua, which is Lua based coding that allows you to add loads of different features to SMBX. 2.0 is still in the beta phase, and is sort of considered the 'official' (ish) continuation of SMBX. I hope I got that all correct.
Also, welcome to the forums!

Is the topic author(UnderYoshi) looking for 1.4.3 download link ?

You find a download link, along with the latest patch here.

Go to the PGE Forums if you need help with 1.4.3.

2.0 has some neat characters, like Bowser. But only a few NPC.
1.4.3 has some Amazing features like New Powerups, Flagpolls, Baby Yoshi, etc.

There both Unofficial, because it's not made by the creator of SMBX, also, Redigit isn't involved with it.

38-A, also referred to SMBX 1.4.3, isn't official in any way, nor is it compatible with the current SMBX, which is the opposite of what the dev team intends to do for SMBX 2.0. While none are official, 2.0 is to be the true successor of 1.3.

2.0 has few NPC.

True, but that is about to change pretty soon. You can also amend for that with Lua, allowing for really cool obstacles you only wish 1.4.3 could do.