So, I just suddenly saw some oil mark on the floor under my passenger side left side. 2 days back I got my car’s link rod, both control arms bushings and ball joint changed.
Attaching the video link below of the exact situation. What it could be?
E250 W212 2014

you call that exact situaton... you have oil leak that looks black so unlikely tranny...

First thing is check oil dipstick marks -
Don't blow up your engine without oil!

With engine cold and stopped proceed to open the engine hood to inspect.
Repeat with underbelly pans.

-- PCV may be involved

-- Intake catch-can may be have filled up without service

-- Rear cam plug may have popped out

-- Oil cooler can leak productively

You can not diagnose this from afar without looking at the engine.

Just checked the engine oil level, currently it’s fine. I am not a professional who exactly knows the technical terms so please bear with me. One thing more , the sway bar bush too seems wet. Car was serviced 2 months back with oil, oil filter, fuel filter and air filter changed.
It’s currently 1 am here and I will be going to the mechanic in the morning. I am really worried what it could be because it’s a maintained car. Top of the car is absolutely dry under the hood

they changed the fuel filter...
what sort of engine type is this ?

This could help us - Can we see that :
"One thing more , the sway bar bush too seems wet'.

Perhaps the ppl who worked on your car can complete the job?
It doesn't sound like oil filter housing is leaking.

Yes fuel filter was due for change! It was last changed 4 years back. I asked him to change it with a new one!

here’s another video

Upon both of your video inspection...
An engine oil leak is confirmed on bank2 side.

Best case scenario the oil filter is leaking
Worse case scenario the oil cooler is leaking.

Once the engine hood gets opened the evidence will help sort the solution.

Bank 2 means?
I forgot to mention it’s a diesel E250 W212 2014

Engine "Bank 2" means the "driver side" in USA.

Next step is take a picture of your E250 engine

No the leak is dripping from co-driver/passenger side (left side in my country)

I see... actually no, I don't see anything.
It's gonna be hard to point out your leak.

Check transmission cooler line to radiator.
That old oil may be coming out of there under pressure.
Check tranny oil.

Should pop over to diesel section as most in this section arent gonna help much with the diesel side.

Not a guru but with the om651 having the oil filter housing on your passenger side (driver side US) and the possibility of the seals going south on these older vehicles that could be a spot. It looks like used engine oil so assume its not from spilling into the injector area when doing oil change.

FYI these are 4 cylinders and dont have the dual banks like a gasser, only one "bank" if you will.

There is no way to check the 4matic trans fluid level I am aware of besides doing the fill procedure

IMHO check the oil filter housing closely, also make sure the oil filter housing insert is properly sealed.

Its not 4matic. And I’ll have a look at oil filter housing

I went to my mechanic and according to him upon opening up the bottom cover shields he found that Intercooler Hose pipe was the culprit and was causing the leak and he replaced it with a new one. But when he showed me the old hose pipe there were no cuts or damage and I asked him the same he said that it’s the seals that sometimes leaks and gets weak due to age (Car age is 10 years old). Is he right?
I don’t know whether the issue is fixed or not as whole night the oil didn’t drained. Currently it’s not dripping

Those hoses provide a flexible connection between the moving, vibrating powerplant and its stationary support components. If some of the variables were calculated, one could surmise this particular hose "flexed" over a concentrated area. Further, materials used in the manufacturing process make up several layers depending on a given application. If any layer fails, pressure will simply move between them and build up until this fluid (or gas) reaches a layer without a resistance to this pressure. If a hose is wet anyplace along its length, it has probably failed.

But how come the hose leaked this much of oil on undertray. Does the hose have this much of oil which is present on the underbody cover.

That really doesn`t look like a big leak and it looks kinda old, probably a small leak over the time so that may not make a noticeable difference on the oil level, if its fixed nothing to worry about, I`d keep an eye on it next few days and if nothing happens just enjoy the ride.