Where to put 从头到尾 in a sentence?

Both sound idiomatic and can be used interchangeably, but both can bring more or less confusion without context. Two ways to understand those sentences :

1. "I've seen his movie (from the beginning to the end) entirely";
2. "I've seen entirely (all of) his movies". (here 電影 is considered as a plural)

This confusion can be solved in either way:

1. say "我从头到尾把他的电影全都看了一遍。" to emphasis you're talking about a collection and that you have seen every single movie of him ;
2. let your interlocutor deduce himself from the film director's recent activities whether you're talking about a collection (old movies) or the movie (the recent one that everybody knows).

This is typical in Chinese: context is everything.

Now, if you are extremely loyal to the etymology, you may feel that 从头到尾 should qualify something having "length". Taking your example, when 从头到尾 is applied to 電影, it's fine, because movies have a running time. However, when 从 头到尾 is applied to a collection (of movies here) is a bit odd. There is other manners to say "every single one", for instance, 悉數. It's all about accuracy. In everyday life, people understand themselves. My point here is to say that under ambiguity, I'd tend to understand the sentence logically, i.e. as "I've seen his movie (from the beginning to the end) entirely". The latter sentence brings more confusion than the former one because when you said "我把他的电影..." we don't know at that point whether is about "movie" or "movies" and then comes the ambiguous adverb 从头到尾.

Bonus, about precision.

There is a similar phenomenon in French with the expression "de A à Z" (from A to Z) which means etymologically "from the beginning to the end". It sounds a bit weird to qualify something hasn't extremities (or more generally, not sorted). But this meaning has later been extended to "entirely" and it's fine to say "J'ai traversé la ville de A à Z" (I crossed the city entirely).

我把他的电影从头到尾看了一遍。

Is more idiomatic. 从头到尾 applies to 电影

我从头到尾把他的电影看了一遍。

Here 从头到尾 applies to 我，which is strange.

Nevertheless, colloquially people can still understand both expressions equally well.

Short answer: "从头到尾" and "把他的电影" are two adverbs having the equal weight, so you can put either one first.

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Detailed answer:

To analysis a chinese sentence, is very important to know the basic structure:

主语 + 谓语 + 宾语.

• 主语 includes the "形容词" ( adjective, which decorates the 主语 )
• 谓语 includes the "副词" ( adverb, which decorates the 谓语 )
• 宾语 includes the "形容词" (adjective)

so, following is a complete structure:

(形容词 + 主语) + (副词 + 谓语 + 副词) + (形容词 + 宾语)

in your example:

我从头到尾把他的电影看了一遍

• 主语: 我
• 谓语: 看
• 副词 before 谓语: 从头到尾, 把他的电影
• 副词 after 谓语: 了, 一遍

make sense.

in your example 2:

我把他的电影从头到尾看了一遍

• 主语: 我
• 谓语: 看
• 副词 before 谓语: 把他的电影, 从头到尾
• 副词 after 谓语: 了, 一遍

you may find that, (把他的电影), (从头到尾) are two adverbs has a position before the 谓语. This is quite common and they often have a equal position.

so, the final explaination is: Both sentence is correct, choose whichever you want.

also other examples:

• 我 开开心心, 嘴里哼着歌地 工作.
• 我 嘴里哼着歌, 开开心心地 工作.

1.我 [从头到尾] 把他的电影看了一遍。

2.我把他的电影 [从头到尾] 看了一遍。

Both are idiomatic.

[从头到尾] is an adverbial phrase that can be placed before or after the object [他的电影]. Just like the two sentences above.

In either case, the adverbial phrase must be placed before the verb phrase [看了一遍]

#1 place the adverbial phrase before the object. It emphasizes the adverbial phrase [从头到尾](from start to finish) -- What do you do from start to finish?

#2 place the object before the adverbial phrase. It emphasizes the object [他的电影] (his movies) -- What do you do to his movies?

1. 我从头到尾把他的电影看了一遍

是把他所有电影全都看了一遍，定义很清晰。

2. 我把他的电影从头到尾看了一遍

是我把他某一部电影从头到尾看了一遍，并且有把他的电影全都看完了的模糊的含义